diff --git a/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_popup.js b/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_popup.js
index 746820adfb26..7f5c5c818340 100644
--- a/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_popup.js
+++ b/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_popup.js
@@ -91,17 +91,7 @@ add_task(async function testWebExtensionsToolboxSwitchToPopup() {
     /* eslint-disable no-undef */
 
     let jsterm;
-    const popupFramePromise = new Promise(resolve => {
-      const listener = data => {
-        if (data.frames.some(({url}) => url && url.endsWith("popup.html"))) {
-          toolbox.target.off("frame-update", listener);
-          resolve();
-        }
-      };
-      toolbox.target.on("frame-update", listener);
-    });
-
-    const waitForFrameListUpdate = toolbox.target.once("frame-update");
+    let popupFramePromise;
 
     toolbox.selectTool("webconsole")
       .then(async (console) => {
@@ -121,6 +111,18 @@ add_task(async function testWebExtensionsToolboxSwitchToPopup() {
         await clickNoAutoHideMenu();
         dump(`Clicked the menu button\n`);
 
+        popupFramePromise = new Promise(resolve => {
+          const listener = data => {
+            if (data.frames.some(({url}) => url && url.endsWith("popup.html"))) {
+              toolbox.target.off("frame-update", listener);
+              resolve();
+            }
+          };
+          toolbox.target.on("frame-update", listener);
+        });
+
+        const waitForFrameListUpdate = toolbox.target.once("frame-update");
+
         jsterm = console.hud.jsterm;
         jsterm.execute("myWebExtensionShowPopup()");
 
diff --git a/devtools/client/accessibility/test/browser/head.js b/devtools/client/accessibility/test/browser/head.js
index 531917a33e31..17b450a57e76 100644
--- a/devtools/client/accessibility/test/browser/head.js
+++ b/devtools/client/accessibility/test/browser/head.js
@@ -408,6 +408,6 @@ function reload(target, waitForTargetEvent = "navigate") {
  * @param  {String} waitForTargetEvent Event to wait for after reload.
  */
 function navigate(target, url, waitForTargetEvent = "navigate") {
-  executeSoon(() => target.activeTab.navigateTo({ url }));
+  executeSoon(() => target.activeTab.navigateTo(url));
   return once(target, waitForTargetEvent);
 }
diff --git a/devtools/client/application/initializer.js b/devtools/client/application/initializer.js
index 4e4f4432c791..683d4859126f 100644
--- a/devtools/client/application/initializer.js
+++ b/devtools/client/application/initializer.js
@@ -43,7 +43,8 @@ window.Application = {
         return toolbox.selectTool(toolId);
       }
     };
-    this.toolbox.target.activeTab.on("workerListChanged", this.updateWorkers);
+
+    this.client.addListener("workerListChanged", this.updateWorkers);
     this.client.addListener("serviceWorkerRegistrationListChanged", this.updateWorkers);
     this.client.addListener("registration-changed", this.updateWorkers);
     this.client.addListener("processListChanged", this.updateWorkers);
@@ -88,7 +89,7 @@ window.Application = {
   },
 
   destroy() {
-    this.toolbox.target.activeTab.off("workerListChanged", this.updateWorkers);
+    this.client.removeListener("workerListChanged", this.updateWorkers);
     this.client.removeListener("serviceWorkerRegistrationListChanged",
       this.updateWorkers);
     this.client.removeListener("registration-changed", this.updateWorkers);
diff --git a/devtools/client/application/test/head.js b/devtools/client/application/test/head.js
index c81d6a2cc2e2..6f6dc9d97884 100644
--- a/devtools/client/application/test/head.js
+++ b/devtools/client/application/test/head.js
@@ -41,7 +41,7 @@ function getWorkerContainers(doc) {
 }
 
 function navigate(target, url, waitForTargetEvent = "navigate") {
-  executeSoon(() => target.activeTab.navigateTo({ url }));
+  executeSoon(() => target.activeTab.navigateTo(url));
   return once(target, waitForTargetEvent);
 }
 
diff --git a/devtools/client/canvasdebugger/test/head.js b/devtools/client/canvasdebugger/test/head.js
index fcbd14ece28d..299ae1ebeb6a 100644
--- a/devtools/client/canvasdebugger/test/head.js
+++ b/devtools/client/canvasdebugger/test/head.js
@@ -107,7 +107,7 @@ function navigateInHistory(aTarget, aDirection, aWaitForTargetEvent = "navigate"
 }
 
 function navigate(aTarget, aUrl, aWaitForTargetEvent = "navigate") {
-  executeSoon(() => aTarget.activeTab.navigateTo({ url: aUrl }));
+  executeSoon(() => aTarget.activeTab.navigateTo(aUrl));
   return once(aTarget, aWaitForTargetEvent);
 }
 
diff --git a/devtools/client/debugger/debugger-controller.js b/devtools/client/debugger/debugger-controller.js
index af4394ece86e..3a194b9b47ac 100644
--- a/devtools/client/debugger/debugger-controller.js
+++ b/devtools/client/debugger/debugger-controller.js
@@ -478,22 +478,11 @@ Workers.prototype = {
     }
 
     this._updateWorkerList();
-
-    // `_tabClient` can be BrowsingContextTargetFront (protocol.js front) or
-    // WorkerClient/DebuggerClient (old fashion client)
-    if (typeof(this._tabClient.on) == "function") {
-      this._tabClient.on("workerListChanged", this._onWorkerListChanged);
-    } else {
-      this._tabClient.addListener("workerListChanged", this._onWorkerListChanged);
-    }
+    this._tabClient.addListener("workerListChanged", this._onWorkerListChanged);
   },
 
   disconnect: function () {
-    if (typeof(this._tabClient.on) == "function") {
-      this._tabClient.off("workerListChanged", this._onWorkerListChanged);
-    } else {
-      this._tabClient.removeListener("workerListChanged", this._onWorkerListChanged);
-    }
+    this._tabClient.removeListener("workerListChanged", this._onWorkerListChanged);
   },
 
   _updateWorkerList: function () {
diff --git a/devtools/client/debugger/new/src/client/firefox/commands.js b/devtools/client/debugger/new/src/client/firefox/commands.js
index 5698dc744475..16415c5620bc 100644
--- a/devtools/client/debugger/new/src/client/firefox/commands.js
+++ b/devtools/client/debugger/new/src/client/firefox/commands.js
@@ -247,7 +247,7 @@ function debuggeeCommand(script) {
 }
 
 function navigate(url) {
-  return tabTarget.activeTab.navigateTo({ url });
+  return tabTarget.activeTab.navigateTo(url);
 }
 
 function reload() {
@@ -455,4 +455,4 @@ const clientCommands = {
   setSkipPausing
 };
 exports.setupCommands = setupCommands;
-exports.clientCommands = clientCommands;
+exports.clientCommands = clientCommands;
\ No newline at end of file
diff --git a/devtools/client/debugger/new/src/client/firefox/events.js b/devtools/client/debugger/new/src/client/firefox/events.js
index 6499900453f6..ee297a88dbdb 100644
--- a/devtools/client/debugger/new/src/client/firefox/events.js
+++ b/devtools/client/debugger/new/src/client/firefox/events.js
@@ -41,13 +41,7 @@ function setupEvents(dependencies) {
     });
 
     if (threadClient._parent) {
-      // Parent may be BrowsingContextTargetFront and be protocol.js.
-      // Or DebuggerClient/WorkerClient and still be old fashion actor.
-      if (threadClient._parent.on) {
-        threadClient._parent.on("workerListChanged", workerListChanged);
-      } else {
-        threadClient._parent.addListener("workerListChanged", workerListChanged);
-      }
+      threadClient._parent.addListener("workerListChanged", workerListChanged);
     }
   }
 }
@@ -119,4 +113,4 @@ const clientEvents = {
   newSource
 };
 exports.setupEvents = setupEvents;
-exports.clientEvents = clientEvents;
+exports.clientEvents = clientEvents;
\ No newline at end of file
diff --git a/devtools/client/debugger/new/test/mochitest/browser_dbg-inline-cache.js b/devtools/client/debugger/new/test/mochitest/browser_dbg-inline-cache.js
index c7291752fa71..5c7c0a50b8e5 100644
--- a/devtools/client/debugger/new/test/mochitest/browser_dbg-inline-cache.js
+++ b/devtools/client/debugger/new/test/mochitest/browser_dbg-inline-cache.js
@@ -76,7 +76,7 @@ add_task(async function() {
   );
 
   info("Disable HTTP cache for page");
-  await toolbox.target.activeTab.reconfigure({ options: { cacheDisabled: true } });
+  await toolbox.target.activeTab.reconfigure({ cacheDisabled: true });
   makeChanges();
 
   info("Reload inside debugger with toolbox caching disabled (attempt 1)");
@@ -106,7 +106,7 @@ add_task(async function() {
   );
 
   info("Enable HTTP cache for page");
-  await toolbox.target.activeTab.reconfigure({ options: { cacheDisabled: false } });
+  await toolbox.target.activeTab.reconfigure({ cacheDisabled: false });
   makeChanges();
 
   // Even though the HTTP cache is now enabled, Gecko sets the VALIDATE_ALWAYS flag when
diff --git a/devtools/client/debugger/test/mochitest/head.js b/devtools/client/debugger/test/mochitest/head.js
index 63db76e75fc6..83ef63c11596 100644
--- a/devtools/client/debugger/test/mochitest/head.js
+++ b/devtools/client/debugger/test/mochitest/head.js
@@ -180,8 +180,8 @@ function getAddonActorForId(aClient, aAddonId) {
 
 async function attachTargetActorForUrl(aClient, aUrl) {
   let grip = await getTargetActorForUrl(aClient, aUrl);
-  let [ response, front ] = await aClient.attachTarget(grip.actor);
-  return [grip, response, front];
+  let [ response ] = await aClient.attachTarget(grip.actor);
+  return [grip, response];
 }
 
 async function attachThreadActorForUrl(aClient, aUrl) {
@@ -450,7 +450,7 @@ function ensureThreadClientState(aPanel, aState) {
 
 function reload(aPanel, aUrl) {
   let activeTab = aPanel.panelWin.DebuggerController._target.activeTab;
-  aUrl ? activeTab.navigateTo({ url: aUrl }) : activeTab.reload();
+  aUrl ? activeTab.navigateTo(aUrl) : activeTab.reload();
 }
 
 function navigateActiveTabTo(aPanel, aUrl, aWaitForEventName, aEventRepeat) {
@@ -1109,9 +1109,14 @@ function attachWorker(tabClient, worker) {
   return tabClient.attachWorker(worker.actor);
 }
 
-function waitForWorkerListChanged(targetFront) {
+function waitForWorkerListChanged(tabClient) {
   info("Waiting for worker list to change.");
-  return targetFront.once("workerListChanged");
+  return new Promise(function (resolve) {
+    tabClient.addListener("workerListChanged", function listener() {
+      tabClient.removeListener("workerListChanged", listener);
+      resolve();
+    });
+  });
 }
 
 function attachThread(workerClient, options) {
diff --git a/devtools/client/framework/target.js b/devtools/client/framework/target.js
index 193cae5fd0cf..c11e813b315e 100644
--- a/devtools/client/framework/target.js
+++ b/devtools/client/framework/target.js
@@ -194,7 +194,6 @@ const TargetFactory = exports.TargetFactory = {
 function TabTarget({ form, client, chrome, tab = null }) {
   EventEmitter.decorate(this);
   this.destroy = this.destroy.bind(this);
-  this._onTabNavigated = this._onTabNavigated.bind(this);
   this.activeTab = this.activeConsole = null;
 
   this._form = form;
@@ -519,12 +518,6 @@ TabTarget.prototype = {
       const [response, tabClient] = await this._client.attachTarget(this._form.actor);
       this.activeTab = tabClient;
       this.threadActor = response.threadActor;
-
-      this.activeTab.on("tabNavigated", this._onTabNavigated);
-      this._onFrameUpdate = packet => {
-        this.emit("frame-update", packet);
-      };
-      this.activeTab.on("frameUpdate", this._onFrameUpdate);
     };
 
     // Attach the console actor
@@ -556,6 +549,8 @@ TabTarget.prototype = {
         this._title = form.title;
       }
 
+      this._setupRemoteListeners();
+
       // AddonActor and chrome debugging on RootActor don't inherit from
       // BrowsingContextTargetActor (i.e. this.isBrowsingContext=false) and don't need
       // to be attached.
@@ -563,10 +558,6 @@ TabTarget.prototype = {
         await attachTarget();
       }
 
-      // _setupRemoteListeners has to be called after the potential call to `attachTarget`
-      // as it depends on `activeTab` which is set by this method.
-      this._setupRemoteListeners();
-
       // But all target actor have a console actor to attach
       return attachConsole();
     })();
@@ -594,95 +585,70 @@ TabTarget.prototype = {
     this._tab.removeEventListener("TabRemotenessChange", this);
   },
 
-  /**
-   * Event listener for tabNavigated packet sent by activeTab's front.
-   */
-  _onTabNavigated: function(packet) {
-    const event = Object.create(null);
-    event.url = packet.url;
-    event.title = packet.title;
-    event.nativeConsoleAPI = packet.nativeConsoleAPI;
-    event.isFrameSwitching = packet.isFrameSwitching;
-
-    // Keep the title unmodified when a developer toolbox switches frame
-    // for a tab (Bug 1261687), but always update the title when the target
-    // is a WebExtension (where the addon name is always included in the title
-    // and the url is supposed to be updated every time the selected frame changes).
-    if (!packet.isFrameSwitching || this.isWebExtension) {
-      this._url = packet.url;
-      this._title = packet.title;
-    }
-
-    // Send any stored event payload (DOMWindow or nsIRequest) for backwards
-    // compatibility with non-remotable tools.
-    if (packet.state == "start") {
-      event._navPayload = this._navRequest;
-      this.emit("will-navigate", event);
-      this._navRequest = null;
-    } else {
-      event._navPayload = this._navWindow;
-      this.emit("navigate", event);
-      this._navWindow = null;
-    }
-  },
-
   /**
    * Setup listeners for remote debugging, updating existing ones as necessary.
    */
   _setupRemoteListeners: function() {
     this.client.addListener("closed", this.destroy);
 
-    // For now, only browsing-context inherited actors are using a front,
-    // for which events have to be listened on the front itself.
-    // For other actors (ContentProcessTargetActor and AddonTargetActor), events should
-    // still be listened directly on the client. This should be ultimately cleaned up to
-    // only listen from a front by bug 1465635.
-    if (this.activeTab) {
-      this.activeTab.on("tabDetached", this.destroy);
+    this._onTabDetached = (type, packet) => {
+      // We have to filter message to ensure that this detach is for this tab
+      if (packet.from == this._form.actor) {
+        this.destroy();
+      }
+    };
+    this.client.addListener("tabDetached", this._onTabDetached);
 
-      // These events should be ultimately listened from the thread client as
-      // they are coming from it and no longer go through the Target Actor/Front.
-      this._onSourceUpdated = packet => this.emit("source-updated", packet);
-      this.activeTab.on("newSource", this._onSourceUpdated);
-      this.activeTab.on("updatedSource", this._onSourceUpdated);
-    } else {
-      this._onTabDetached = (type, packet) => {
-        // We have to filter message to ensure that this detach is for this tab
-        if (packet.from == this._form.actor) {
-          this.destroy();
-        }
-      };
-      this.client.addListener("tabDetached", this._onTabDetached);
+    this._onTabNavigated = (type, packet) => {
+      const event = Object.create(null);
+      event.url = packet.url;
+      event.title = packet.title;
+      event.nativeConsoleAPI = packet.nativeConsoleAPI;
+      event.isFrameSwitching = packet.isFrameSwitching;
 
-      this._onSourceUpdated = (type, packet) => this.emit("source-updated", packet);
-      this.client.addListener("newSource", this._onSourceUpdated);
-      this.client.addListener("updatedSource", this._onSourceUpdated);
-    }
+      // Keep the title unmodified when a developer toolbox switches frame
+      // for a tab (Bug 1261687), but always update the title when the target
+      // is a WebExtension (where the addon name is always included in the title
+      // and the url is supposed to be updated every time the selected frame changes).
+      if (!packet.isFrameSwitching || this.isWebExtension) {
+        this._url = packet.url;
+        this._title = packet.title;
+      }
+
+      // Send any stored event payload (DOMWindow or nsIRequest) for backwards
+      // compatibility with non-remotable tools.
+      if (packet.state == "start") {
+        event._navPayload = this._navRequest;
+        this.emit("will-navigate", event);
+        this._navRequest = null;
+      } else {
+        event._navPayload = this._navWindow;
+        this.emit("navigate", event);
+        this._navWindow = null;
+      }
+    };
+    this.client.addListener("tabNavigated", this._onTabNavigated);
+
+    this._onFrameUpdate = (type, packet) => {
+      this.emit("frame-update", packet);
+    };
+    this.client.addListener("frameUpdate", this._onFrameUpdate);
+
+    this._onSourceUpdated = (event, packet) => this.emit("source-updated", packet);
+    this.client.addListener("newSource", this._onSourceUpdated);
+    this.client.addListener("updatedSource", this._onSourceUpdated);
   },
 
   /**
    * Teardown listeners for remote debugging.
    */
   _teardownRemoteListeners: function() {
-    // Remove listeners set in _setupRemoteListeners
     this.client.removeListener("closed", this.destroy);
-    if (this.activeTab) {
-      this.activeTab.off("tabDetached", this.destroy);
-      this.activeTab.off("newSource", this._onSourceUpdated);
-      this.activeTab.off("updatedSource", this._onSourceUpdated);
-    } else {
-      this.client.removeListener("tabDetached", this._onTabDetached);
-      this.client.removeListener("newSource", this._onSourceUpdated);
-      this.client.removeListener("updatedSource", this._onSourceUpdated);
-    }
-
-    // Remove listeners set in attachTarget
-    if (this.activeTab) {
-      this.activeTab.off("tabNavigated", this._onTabNavigated);
-      this.activeTab.off("frameUpdate", this._onFrameUpdate);
-    }
-
-    // Remove listeners set in attachConsole
+    this.client.removeListener("tabNavigated", this._onTabNavigated);
+    this.client.removeListener("tabDetached", this._onTabDetached);
+    this.client.removeListener("frameUpdate", this._onFrameUpdate);
+    this.client.removeListener("newSource", this._onSourceUpdated);
+    this.client.removeListener("updatedSource", this._onSourceUpdated);
     if (this.activeConsole && this._onInspectObject) {
       this.activeConsole.off("inspectObject", this._onInspectObject);
     }
@@ -775,11 +741,7 @@ TabTarget.prototype = {
           // it. We just need to detach from the tab, if already attached.
           // |detach| may fail if the connection is already dead, so proceed with
           // cleanup directly after this.
-          try {
-            await this.activeTab.detach();
-          } catch (e) {
-            console.warn(`Error while detaching target: ${e.message}`);
-          }
+          this.activeTab.detach();
           cleanupAndResolve();
         } else {
           cleanupAndResolve();
@@ -828,7 +790,7 @@ TabTarget.prototype = {
   logErrorInPage: function(text, category) {
     if (this.activeTab && this.activeTab.traits.logInPage) {
       const errorFlag = 0;
-      this.activeTab.logInPage({ text, category, flags: errorFlag });
+      this.activeTab.logInPage(text, category, errorFlag);
     }
   },
 
@@ -843,7 +805,7 @@ TabTarget.prototype = {
   logWarningInPage: function(text, category) {
     if (this.activeTab && this.activeTab.traits.logInPage) {
       const warningFlag = 1;
-      this.activeTab.logInPage({ text, category, flags: warningFlag });
+      this.activeTab.logInPage(text, category, warningFlag);
     }
   },
 };
diff --git a/devtools/client/framework/test/browser_toolbox_target.js b/devtools/client/framework/test/browser_toolbox_target.js
index 49df1d2fb9b8..c6e6941c9b25 100644
--- a/devtools/client/framework/test/browser_toolbox_target.js
+++ b/devtools/client/framework/test/browser_toolbox_target.js
@@ -37,7 +37,7 @@ add_task(async function() {
   const toolbox = await onToolboxReady;
 
   const onToolboxDestroyed = gDevTools.once("toolbox-destroyed");
-  const onTabDetached = toolbox.target.activeTab.once("tabDetached");
+  const onTabDetached = once(toolbox.target.client, "tabDetached");
 
   info("Removing the iframes");
   toolboxIframe.remove();
diff --git a/devtools/client/framework/test/browser_toolbox_tool_remote_reopen.js b/devtools/client/framework/test/browser_toolbox_tool_remote_reopen.js
index 55db7f501a64..66c26d8aed96 100644
--- a/devtools/client/framework/test/browser_toolbox_tool_remote_reopen.js
+++ b/devtools/client/framework/test/browser_toolbox_tool_remote_reopen.js
@@ -115,6 +115,10 @@ function test() {
           todo(false, "Front for " + actor + " still held in pool!");
           continue;
         }
+        // gcliActor is for the commandline which is separate to the toolbox
+        if (actor.includes("gcliActor")) {
+          continue;
+        }
         ok(false, "Front for " + actor + " still held in pool!");
       }
     }
diff --git a/devtools/client/framework/test/helper_disable_cache.js b/devtools/client/framework/test/helper_disable_cache.js
index e8bc73e9236a..c3d62457a4a7 100644
--- a/devtools/client/framework/test/helper_disable_cache.js
+++ b/devtools/client/framework/test/helper_disable_cache.js
@@ -85,12 +85,11 @@ async function setDisableCacheCheckboxChecked(tabX, state) {
 
   if (cbx.checked !== state) {
     info("Setting disable cache checkbox to " + state + " for " + tabX.title);
-    const onReconfigured = tabX.toolbox.once("cache-reconfigured");
     cbx.click();
 
-    // We have to wait for the reconfigure request to be finished before reloading
-    // the page.
-    await onReconfigured;
+    // We need to wait for all checkboxes to be updated and the docshells to
+    // apply the new cache settings.
+    await waitForTick();
   }
 }
 
diff --git a/devtools/client/framework/toolbox-options.js b/devtools/client/framework/toolbox-options.js
index c2f912949836..d74d2cddb807 100644
--- a/devtools/client/framework/toolbox-options.js
+++ b/devtools/client/framework/toolbox-options.js
@@ -460,7 +460,7 @@ OptionsPanel.prototype = {
     }
 
     if (this.target.activeTab && !this.target.chrome) {
-      const response = await this.target.activeTab.attach();
+      const [ response ] = await this.target.client.attachTarget(this.target.activeTab._actor);
       this._origJavascriptEnabled = !response.javascriptEnabled;
       this.disableJSNode.checked = this._origJavascriptEnabled;
       this.disableJSNode.addEventListener("click", this._disableJSClicked);
@@ -512,7 +512,7 @@ OptionsPanel.prototype = {
       "javascriptEnabled": !checked
     };
 
-    this.target.activeTab.reconfigure({ options });
+    this.target.activeTab.reconfigure(options);
   },
 
   destroy: function() {
diff --git a/devtools/client/framework/toolbox.js b/devtools/client/framework/toolbox.js
index a0d215e647b0..e3a8682a870f 100644
--- a/devtools/client/framework/toolbox.js
+++ b/devtools/client/framework/toolbox.js
@@ -1339,21 +1339,12 @@ Toolbox.prototype = {
    * Apply the current cache setting from devtools.cache.disabled to this
    * toolbox's tab.
    */
-  _applyCacheSettings: async function() {
+  _applyCacheSettings: function() {
     const pref = "devtools.cache.disabled";
     const cacheDisabled = Services.prefs.getBoolPref(pref);
 
     if (this.target.activeTab) {
-      await this.target.activeTab.reconfigure({
-        options: {
-          "cacheDisabled": cacheDisabled
-        }
-      });
-
-      // This event is only emitted for tests in order to know when to reload
-      if (flags.testing) {
-        this.emit("cache-reconfigured");
-      }
+      this.target.activeTab.reconfigure({"cacheDisabled": cacheDisabled});
     }
   },
 
@@ -1368,9 +1359,7 @@ Toolbox.prototype = {
 
     if (this.target.activeTab) {
       this.target.activeTab.reconfigure({
-        options: {
-          "serviceWorkersTestingEnabled": serviceWorkersTestingEnabled
-        }
+        "serviceWorkersTestingEnabled": serviceWorkersTestingEnabled
       });
     }
   },
@@ -1416,11 +1405,7 @@ Toolbox.prototype = {
       this.telemetry.toolClosed("paintflashing", this.sessionId, this);
     }
     this.isPaintFlashing = !this.isPaintFlashing;
-    return this.target.activeTab.reconfigure({
-      options: {
-        "paintFlashing": this.isPaintFlashing
-      }
-    });
+    return this.target.activeTab.reconfigure({"paintFlashing": this.isPaintFlashing});
   },
 
   /**
@@ -2343,7 +2328,7 @@ Toolbox.prototype = {
   onSelectFrame: function(frameId) {
     // Send packet to the backend to select specified frame and
     // wait for 'frameUpdate' event packet to update the UI.
-    this.target.activeTab.switchToFrame({ windowId: frameId });
+    this.target.activeTab.switchToFrame(frameId);
   },
 
   /**
diff --git a/devtools/client/inspector/test/browser_inspector_startup.js b/devtools/client/inspector/test/browser_inspector_startup.js
index 5c4b45a94513..8441a75caf95 100644
--- a/devtools/client/inspector/test/browser_inspector_startup.js
+++ b/devtools/client/inspector/test/browser_inspector_startup.js
@@ -42,7 +42,7 @@ add_task(async function() {
 
   info("Navigate to the slow loading page");
   const activeTab = inspector.toolbox.target.activeTab;
-  await activeTab.navigateTo({ url: TEST_URL });
+  await activeTab.navigateTo(TEST_URL);
 
   info("Wait for request made to the image");
   const response = await onRequest;
diff --git a/devtools/client/inspector/test/head.js b/devtools/client/inspector/test/head.js
index 6a21b94f883f..159948eb13a5 100644
--- a/devtools/client/inspector/test/head.js
+++ b/devtools/client/inspector/test/head.js
@@ -48,7 +48,7 @@ var navigateTo = async function(inspector, url) {
 
   info("Navigating to: " + url);
   const activeTab = inspector.toolbox.target.activeTab;
-  await activeTab.navigateTo({ url });
+  await activeTab.navigateTo(url);
 
   info("Waiting for markup view to load after navigation.");
   await markuploaded;
diff --git a/devtools/client/netmonitor/src/connector/firefox-connector.js b/devtools/client/netmonitor/src/connector/firefox-connector.js
index 81f4bb7a6294..59dbbc15ef4b 100644
--- a/devtools/client/netmonitor/src/connector/firefox-connector.js
+++ b/devtools/client/netmonitor/src/connector/firefox-connector.js
@@ -316,7 +316,7 @@ class FirefoxConnector {
 
     // Reconfigures the tab, optionally triggering a reload.
     const reconfigureTab = options => {
-      return this.tabTarget.activeTab.reconfigure({ options });
+      return this.tabTarget.activeTab.reconfigure(options);
     };
 
     // Reconfigures the tab and waits for the target to finish navigating.
diff --git a/devtools/client/netmonitor/test/head.js b/devtools/client/netmonitor/test/head.js
index e0e2b80b1a86..01a1bbcc2e34 100644
--- a/devtools/client/netmonitor/test/head.js
+++ b/devtools/client/netmonitor/test/head.js
@@ -144,7 +144,7 @@ function toggleCache(target, disabled) {
   // Disable the cache for any toolbox that it is opened from this point on.
   Services.prefs.setBoolPref("devtools.cache.disabled", disabled);
 
-  return target.activeTab.reconfigure({ options }).then(() => navigationFinished);
+  return target.activeTab.reconfigure(options).then(() => navigationFinished);
 }
 
 /**
diff --git a/devtools/client/shadereditor/test/head.js b/devtools/client/shadereditor/test/head.js
index 6a97ffef7f49..0fdcb847ed07 100644
--- a/devtools/client/shadereditor/test/head.js
+++ b/devtools/client/shadereditor/test/head.js
@@ -131,7 +131,7 @@ function navigateInHistory(aTarget, aDirection, aWaitForTargetEvent = "navigate"
 }
 
 function navigate(aTarget, aUrl, aWaitForTargetEvent = "navigate") {
-  executeSoon(() => aTarget.activeTab.navigateTo({ url: aUrl }));
+  executeSoon(() => aTarget.activeTab.navigateTo(aUrl));
   return once(aTarget, aWaitForTargetEvent);
 }
 
diff --git a/devtools/client/shared/test/browser_dbg_listtabs-03.js b/devtools/client/shared/test/browser_dbg_listtabs-03.js
index 2d735b52ff0a..941c61f7a222 100644
--- a/devtools/client/shared/test/browser_dbg_listtabs-03.js
+++ b/devtools/client/shared/test/browser_dbg_listtabs-03.js
@@ -11,41 +11,51 @@
 
 var { DebuggerServer } = require("devtools/server/main");
 var { DebuggerClient } = require("devtools/shared/client/debugger-client");
+var { Task } = require("devtools/shared/task");
 
 const TAB1_URL = EXAMPLE_URL + "doc_empty-tab-01.html";
 
-add_task(async function test() {
+var gClient;
+
+function test() {
   DebuggerServer.init();
   DebuggerServer.registerAllActors();
 
   const transport = DebuggerServer.connectPipe();
-  const client = new DebuggerClient(transport);
-  const [type] = await client.connect();
-  is(type, "browser", "Root actor should identify itself as a browser.");
-  const tab = await addTab(TAB1_URL);
+  gClient = new DebuggerClient(transport);
+  gClient.connect().then(Task.async(function* ([aType, aTraits]) {
+    is(aType, "browser",
+      "Root actor should identify itself as a browser.");
+    const tab = yield addTab(TAB1_URL);
 
-  let { tabs } = await client.listTabs();
-  is(tabs.length, 2, "Should be two tabs");
-  const tabGrip = tabs.filter(a => a.url == TAB1_URL).pop();
-  ok(tabGrip, "Should have an actor for the tab");
+    let { tabs } = yield gClient.listTabs();
+    is(tabs.length, 2, "Should be two tabs");
+    const tabGrip = tabs.filter(a => a.url == TAB1_URL).pop();
+    ok(tabGrip, "Should have an actor for the tab");
 
-  let [response, targetFront] = await client.attachTarget(tabGrip.actor);
-  is(response.type, "tabAttached", "Should have attached");
+    let response = yield gClient.request({ to: tabGrip.actor, type: "attach" });
+    is(response.type, "tabAttached", "Should have attached");
 
-  response = await client.listTabs();
-  tabs = response.tabs;
+    response = yield gClient.listTabs();
+    tabs = response.tabs;
 
-  response = await targetFront.detach();
-  is(response.type, "detached", "Should have detached");
+    response = yield gClient.request({ to: tabGrip.actor, type: "detach" });
+    is(response.type, "detached", "Should have detached");
 
-  const newGrip = tabs.filter(a => a.url == TAB1_URL).pop();
-  is(newGrip.actor, tabGrip.actor, "Should have the same actor for the same tab");
+    const newGrip = tabs.filter(a => a.url == TAB1_URL).pop();
+    is(newGrip.actor, tabGrip.actor, "Should have the same actor for the same tab");
 
-  [response, targetFront] = await client.attachTarget(tabGrip.actor);
-  is(response.type, "tabAttached", "Should have attached");
-  response = await targetFront.detach();
-  is(response.type, "detached", "Should have detached");
+    response = yield gClient.request({ to: tabGrip.actor, type: "attach" });
+    is(response.type, "tabAttached", "Should have attached");
+    response = yield gClient.request({ to: tabGrip.actor, type: "detach" });
+    is(response.type, "detached", "Should have detached");
 
-  await removeTab(tab);
-  await client.close();
+    yield removeTab(tab);
+    yield gClient.close();
+    finish();
+  }));
+}
+
+registerCleanupFunction(function() {
+  gClient = null;
 });
diff --git a/devtools/client/shared/test/browser_dbg_navigation.js b/devtools/client/shared/test/browser_dbg_navigation.js
index 53a77fceadf9..a7bc37249e33 100644
--- a/devtools/client/shared/test/browser_dbg_navigation.js
+++ b/devtools/client/shared/test/browser_dbg_navigation.js
@@ -39,10 +39,10 @@ function test() {
   });
 }
 
-function testNavigate(targetFront) {
+function testNavigate([aGrip, aResponse]) {
   const outstanding = [promise.defer(), promise.defer()];
 
-  targetFront.on("tabNavigated", function onTabNavigated(packet) {
+  gClient.addListener("tabNavigated", function onTabNavigated(event, packet) {
     is(packet.url.split("/").pop(), TAB2_FILE,
       "Got a tab navigation notification.");
 
@@ -54,27 +54,27 @@ function testNavigate(targetFront) {
       outstanding[0].resolve();
     } else {
       ok(true, "Tab finished navigating.");
-      targetFront.off("tabNavigated", onTabNavigated);
+      gClient.removeListener("tabNavigated", onTabNavigated);
       outstanding[1].resolve();
     }
   });
 
   BrowserTestUtils.loadURI(gBrowser.selectedBrowser, TAB2_URL);
   return promise.all(outstanding.map(e => e.promise))
-                .then(() => targetFront);
+                .then(() => aGrip.actor);
 }
 
-async function testDetach(targetFront) {
-  const onDetached = targetFront.once("tabDetached");
+function testDetach(actor) {
+  const deferred = promise.defer();
+
+  gClient.addOneTimeListener("tabDetached", (type, packet) => {
+    ok(true, "Got a tab detach notification.");
+    is(packet.from, actor, "tab detach message comes from the expected actor");
+    deferred.resolve(gClient.close());
+  });
 
   removeTab(gBrowser.selectedTab);
-
-  const packet = await onDetached;
-  ok(true, "Got a tab detach notification.");
-  is(packet.from, targetFront.actorID,
-    "tab detach message comes from the expected actor");
-
-  return gClient.close();
+  return deferred.promise;
 }
 
 registerCleanupFunction(function() {
@@ -83,8 +83,8 @@ registerCleanupFunction(function() {
 
 async function attachTargetActorForUrl(client, url) {
   const grip = await getTargetActorForUrl(client, url);
-  const [, targetFront] = await client.attachTarget(grip.actor);
-  return targetFront;
+  const [ response ] = await client.attachTarget(grip.actor);
+  return [grip, response];
 }
 
 function getTargetActorForUrl(client, url) {
diff --git a/devtools/client/webaudioeditor/test/head.js b/devtools/client/webaudioeditor/test/head.js
index 08cf88aa55bc..1680e3b7ce12 100644
--- a/devtools/client/webaudioeditor/test/head.js
+++ b/devtools/client/webaudioeditor/test/head.js
@@ -48,7 +48,7 @@ function reload(aTarget, aWaitForTargetEvent = "navigate") {
 }
 
 function navigate(aTarget, aUrl, aWaitForTargetEvent = "navigate") {
-  executeSoon(() => aTarget.activeTab.navigateTo({ url: aUrl }));
+  executeSoon(() => aTarget.activeTab.navigateTo(aUrl));
   return once(aTarget, aWaitForTargetEvent);
 }
 
diff --git a/devtools/client/webide/modules/tab-store.js b/devtools/client/webide/modules/tab-store.js
index 8429f524ba72..aed0a7223cf7 100644
--- a/devtools/client/webide/modules/tab-store.js
+++ b/devtools/client/webide/modules/tab-store.js
@@ -61,11 +61,15 @@ TabStore.prototype = {
       // Watch for changes to remote browser tabs
       this._connection.client.addListener("tabListChanged",
                                           this._onTabListChanged);
+      this._connection.client.addListener("tabNavigated",
+                                          this._onTabNavigated);
       this.listTabs();
     } else {
       if (this._connection.client) {
         this._connection.client.removeListener("tabListChanged",
                                                this._onTabListChanged);
+        this._connection.client.removeListener("tabNavigated",
+                                               this._onTabNavigated);
       }
       this._resetStore();
     }
diff --git a/devtools/docs/backend/client-api.md b/devtools/docs/backend/client-api.md
index cd843fcac275..89c889aa8f2a 100644
--- a/devtools/docs/backend/client-api.md
+++ b/devtools/docs/backend/client-api.md
@@ -21,6 +21,8 @@ function start() {
   // Start the client.
   client = new DebuggerClient(transport);
 
+  // Attach listeners for client events.
+  client.addListener("tabNavigated", onTab);
   client.connect((type, traits) => {
     // Now the client is conected to the server.
     debugTab();
@@ -49,6 +51,9 @@ async function startClient() {
   // Start the client.
   client = new DebuggerClient(transport);
 
+  // Attach listeners for client events.
+  client.addListener("tabNavigated", onTab);
+
   client.connect((type, traits) => {
     // Now the client is conected to the server.
     debugTab();
@@ -84,9 +89,6 @@ function attachToTab() {
       }
 
       // Now the tabClient is ready and can be used.
-
-      // Attach listeners for client events.
-      tabClient.addListener("tabNavigated", onTab);
     });
   });
 }
@@ -103,7 +105,7 @@ async function onTab() {
   // Detach from the previous thread.
   await client.activeThread.detach();
   // Detach from the previous tab.
-  await tabClient.activeTab.detach();
+  await client.activeTab.detach();
   // Start debugging the new tab.
   start();
 }
@@ -167,6 +169,8 @@ function startDebugger() {
 
   // Start the client.
   client = new DebuggerClient(transport);
+  // Attach listeners for client events.
+  client.addListener("tabNavigated", onTab);
   client.connect((type, traits) => {
     // Now the client is conected to the server.
     debugTab();
diff --git a/devtools/server/actors/targets/browsing-context.js b/devtools/server/actors/targets/browsing-context.js
index 51402370cfae..c9d10e93dac0 100644
--- a/devtools/server/actors/targets/browsing-context.js
+++ b/devtools/server/actors/targets/browsing-context.js
@@ -966,7 +966,7 @@ const browsingContextTargetPrototype = {
     // subsequent navigation event packet.
     Services.tm.dispatchToMainThread(DevToolsUtils.makeInfallible(() => {
       this.window.location = request.url;
-    }, "BrowsingContextTargetActor.prototype.navigateTo's delayed body:" + request.url));
+    }, "BrowsingContextTargetActor.prototype.navigateTo's delayed body"));
     return {};
   },
 
diff --git a/devtools/server/tests/browser/browser_navigateEvents.js b/devtools/server/tests/browser/browser_navigateEvents.js
index 974b85ee06f7..bdb314f0fc3d 100644
--- a/devtools/server/tests/browser/browser_navigateEvents.js
+++ b/devtools/server/tests/browser/browser_navigateEvents.js
@@ -102,12 +102,12 @@ async function connectAndAttachTab() {
   // Connect to this tab
   const transport = DebuggerServer.connectPipe();
   const client = new DebuggerClient(transport);
-  const form = await connectDebuggerClient(client);
-  const actorID = form.actor;
-  const [, targetFront ] = await client.attachTarget(actorID);
-  targetFront.on("tabNavigated", function(packet) {
+  client.addListener("tabNavigated", function(event, packet) {
     assertEvent("tabNavigated", packet);
   });
+  const form = await connectDebuggerClient(client);
+  const actorID = form.actor;
+  await client.attachTarget(actorID);
   return { client, actorID };
 }
 
diff --git a/devtools/server/tests/browser/browser_webextension_inspected_window.js b/devtools/server/tests/browser/browser_webextension_inspected_window.js
index d642116a049a..502543e3ac58 100644
--- a/devtools/server/tests/browser/browser_webextension_inspected_window.js
+++ b/devtools/server/tests/browser/browser_webextension_inspected_window.js
@@ -26,7 +26,7 @@ async function setup(pageUrl) {
 
   const { client, form } = target;
 
-  const [, targetFront] = await client.attachTarget(form.actor);
+  const [, tabClient] = await client.attachTarget(form.actor);
 
   const [, consoleClient] = await client.attachConsole(form.consoleActor, []);
 
@@ -34,7 +34,7 @@ async function setup(pageUrl) {
 
   return {
     client, form,
-    targetFront, consoleClient,
+    tabClient, consoleClient,
     inspectedWindowFront,
     extension, fakeExtCallerInfo,
   };
@@ -47,11 +47,11 @@ async function teardown({client, extension}) {
   await extension.unload();
 }
 
-function waitForNextTabNavigated(targetFront) {
+function waitForNextTabNavigated(client) {
   return new Promise(resolve => {
-    targetFront.on("tabNavigated", function tabNavigatedListener(pkt) {
+    client.addListener("tabNavigated", function tabNavigatedListener(evt, pkt) {
       if (pkt.state == "stop" && !pkt.isFrameSwitching) {
-        targetFront.off("tabNavigated", tabNavigatedListener);
+        client.removeListener("tabNavigated", tabNavigatedListener);
         resolve();
       }
     });
@@ -227,12 +227,12 @@ add_task(async function test_exception_inspectedWindowEval_result() {
 add_task(async function test_exception_inspectedWindowReload() {
   const {
     client, consoleClient, inspectedWindowFront,
-    extension, fakeExtCallerInfo, targetFront,
+    extension, fakeExtCallerInfo,
   } = await setup(`${TEST_RELOAD_URL}?test=cache`);
 
   // Test reload with bypassCache=false.
 
-  const waitForNoBypassCacheReload = waitForNextTabNavigated(targetFront);
+  const waitForNoBypassCacheReload = waitForNextTabNavigated(client);
   const reloadResult = await inspectedWindowFront.reload(fakeExtCallerInfo,
                                                          {ignoreCache: false});
 
@@ -248,7 +248,7 @@ add_task(async function test_exception_inspectedWindowReload() {
 
   // Test reload with bypassCache=true.
 
-  const waitForForceBypassCacheReload = waitForNextTabNavigated(targetFront);
+  const waitForForceBypassCacheReload = waitForNextTabNavigated(client);
   await inspectedWindowFront.reload(fakeExtCallerInfo, {ignoreCache: true});
 
   await waitForForceBypassCacheReload;
@@ -265,12 +265,12 @@ add_task(async function test_exception_inspectedWindowReload() {
 add_task(async function test_exception_inspectedWindowReload_customUserAgent() {
   const {
     client, consoleClient, inspectedWindowFront,
-    extension, fakeExtCallerInfo, targetFront,
+    extension, fakeExtCallerInfo,
   } = await setup(`${TEST_RELOAD_URL}?test=user-agent`);
 
   // Test reload with custom userAgent.
 
-  const waitForCustomUserAgentReload = waitForNextTabNavigated(targetFront);
+  const waitForCustomUserAgentReload = waitForNextTabNavigated(client);
   await inspectedWindowFront.reload(fakeExtCallerInfo,
                                     {userAgent: "Customized User Agent"});
 
@@ -284,7 +284,7 @@ add_task(async function test_exception_inspectedWindowReload_customUserAgent() {
 
   // Test reload with no custom userAgent.
 
-  const waitForNoCustomUserAgentReload = waitForNextTabNavigated(targetFront);
+  const waitForNoCustomUserAgentReload = waitForNextTabNavigated(client);
   await inspectedWindowFront.reload(fakeExtCallerInfo, {});
 
   await waitForNoCustomUserAgentReload;
@@ -301,12 +301,12 @@ add_task(async function test_exception_inspectedWindowReload_customUserAgent() {
 add_task(async function test_exception_inspectedWindowReload_injectedScript() {
   const {
     client, consoleClient, inspectedWindowFront,
-    extension, fakeExtCallerInfo, targetFront,
+    extension, fakeExtCallerInfo,
   } = await setup(`${TEST_RELOAD_URL}?test=injected-script&frames=3`);
 
   // Test reload with an injectedScript.
 
-  const waitForInjectedScriptReload = waitForNextTabNavigated(targetFront);
+  const waitForInjectedScriptReload = waitForNextTabNavigated(client);
   await inspectedWindowFront.reload(fakeExtCallerInfo,
                                     {injectedScript: `new ${injectedScript}`});
   await waitForInjectedScriptReload;
@@ -321,7 +321,7 @@ add_task(async function test_exception_inspectedWindowReload_injectedScript() {
 
   // Test reload without an injectedScript.
 
-  const waitForNoInjectedScriptReload = waitForNextTabNavigated(targetFront);
+  const waitForNoInjectedScriptReload = waitForNextTabNavigated(client);
   await inspectedWindowFront.reload(fakeExtCallerInfo, {});
   await waitForNoInjectedScriptReload;
 
@@ -339,13 +339,13 @@ add_task(async function test_exception_inspectedWindowReload_injectedScript() {
 add_task(async function test_exception_inspectedWindowReload_multiple_calls() {
   const {
     client, consoleClient, inspectedWindowFront,
-    extension, fakeExtCallerInfo, targetFront,
+    extension, fakeExtCallerInfo,
   } = await setup(`${TEST_RELOAD_URL}?test=user-agent`);
 
   // Test reload with custom userAgent three times (and then
   // check that only the first one has affected the page reload.
 
-  const waitForCustomUserAgentReload = waitForNextTabNavigated(targetFront);
+  const waitForCustomUserAgentReload = waitForNextTabNavigated(client);
 
   inspectedWindowFront.reload(fakeExtCallerInfo, {userAgent: "Customized User Agent 1"});
   inspectedWindowFront.reload(fakeExtCallerInfo, {userAgent: "Customized User Agent 2"});
@@ -360,7 +360,7 @@ add_task(async function test_exception_inspectedWindowReload_multiple_calls() {
 
   // Test reload with no custom userAgent.
 
-  const waitForNoCustomUserAgentReload = waitForNextTabNavigated(targetFront);
+  const waitForNoCustomUserAgentReload = waitForNextTabNavigated(client);
   await inspectedWindowFront.reload(fakeExtCallerInfo, {});
 
   await waitForNoCustomUserAgentReload;
@@ -377,12 +377,12 @@ add_task(async function test_exception_inspectedWindowReload_multiple_calls() {
 add_task(async function test_exception_inspectedWindowReload_stopped() {
   const {
     client, consoleClient, inspectedWindowFront,
-    extension, fakeExtCallerInfo, targetFront,
+    extension, fakeExtCallerInfo,
   } = await setup(`${TEST_RELOAD_URL}?test=injected-script&frames=3`);
 
   // Test reload on a page that calls window.stop() immediately during the page loading
 
-  const waitForPageLoad = waitForNextTabNavigated(targetFront);
+  const waitForPageLoad = waitForNextTabNavigated(client);
   await inspectedWindowFront.eval(fakeExtCallerInfo,
                                   "window.location += '&stop=windowStop'");
 
@@ -390,7 +390,7 @@ add_task(async function test_exception_inspectedWindowReload_stopped() {
   await waitForPageLoad;
 
   info("Starting a reload with an injectedScript");
-  const waitForInjectedScriptReload = waitForNextTabNavigated(targetFront);
+  const waitForInjectedScriptReload = waitForNextTabNavigated(client);
   await inspectedWindowFront.reload(fakeExtCallerInfo,
                                     {injectedScript: `new ${injectedScript}`});
   await waitForInjectedScriptReload;
@@ -408,7 +408,7 @@ add_task(async function test_exception_inspectedWindowReload_stopped() {
   // Reload again with no options.
 
   info("Reload the tab again without any reload options");
-  const waitForNoInjectedScriptReload = waitForNextTabNavigated(targetFront);
+  const waitForNoInjectedScriptReload = waitForNextTabNavigated(client);
   await inspectedWindowFront.reload(fakeExtCallerInfo, {});
   await waitForNoInjectedScriptReload;
 
diff --git a/devtools/server/tests/mochitest/test_webextension-addon-debugging-connect.html b/devtools/server/tests/mochitest/test_webextension-addon-debugging-connect.html
index 7d41b9daeaa6..816e9b3b3153 100644
--- a/devtools/server/tests/mochitest/test_webextension-addon-debugging-connect.html
+++ b/devtools/server/tests/mochitest/test_webextension-addon-debugging-connect.html
@@ -42,6 +42,7 @@ async function test_connect_addon(oopMode) {
   ok(addonTargetActor, "The expected webextension addon actor has been found");
 
   // Connect to the target addon actor and wait for the updated list of frames.
+  const waitFramesUpdated = waitForFramesUpdated({client});
   const addonTarget = await TargetFactory.forRemoteTab({
     form: addonTargetActor,
     client,
@@ -49,7 +50,7 @@ async function test_connect_addon(oopMode) {
   });
   is(addonTarget.form.isOOP, oopMode,
      "Got the expected oop mode in the webextension actor form");
-  const frames = await waitForFramesUpdated(addonTarget);
+  const frames = await waitFramesUpdated;
   const backgroundPageFrame = frames.filter((frame) => {
     return frame.url && frame.url.endsWith("/_generated_background_page.html");
   }).pop();
diff --git a/devtools/server/tests/mochitest/webextension-helpers.js b/devtools/server/tests/mochitest/webextension-helpers.js
index ab180044031b..29e465069953 100644
--- a/devtools/server/tests/mochitest/webextension-helpers.js
+++ b/devtools/server/tests/mochitest/webextension-helpers.js
@@ -51,19 +51,19 @@ function setWebExtensionOOPMode(oopMode) {
   });
 }
 
-function waitForFramesUpdated(target, matchFn) {
+function waitForFramesUpdated({client}, matchFn) {
   return new Promise(resolve => {
-    const listener = data => {
+    const listener = (evt, data) => {
       if (typeof matchFn === "function" && !matchFn(data)) {
         return;
       } else if (!data.frames) {
         return;
       }
 
-      target.activeTab.off("frameUpdate", listener);
+      client.removeListener("frameUpdate", listener);
       resolve(data.frames);
     };
-    target.activeTab.on("frameUpdate", listener);
+    client.addListener("frameUpdate", listener);
   });
 }
 
diff --git a/devtools/server/tests/unit/test_sourcemaps-01.js b/devtools/server/tests/unit/test_sourcemaps-01.js
index fe0b7f74aee2..8c59d2d488ab 100644
--- a/devtools/server/tests/unit/test_sourcemaps-01.js
+++ b/devtools/server/tests/unit/test_sourcemaps-01.js
@@ -44,7 +44,7 @@ function test_simple_source_map() {
     expectedSources.delete(packet.source.url);
 
     if (expectedSources.size === 0) {
-      gThreadClient.removeListener("newSource", _onNewSource);
+      gClient.removeListener("newSource", _onNewSource);
       finishClient(gClient);
     }
   });
diff --git a/devtools/shared/client/constants.js b/devtools/shared/client/constants.js
index ef016cf1d8cd..ccf4605240b4 100644
--- a/devtools/shared/client/constants.js
+++ b/devtools/shared/client/constants.js
@@ -33,16 +33,13 @@ const UnsolicitedNotifications = {
   "addonListChanged": "addonListChanged",
   "workerListChanged": "workerListChanged",
   "serviceWorkerRegistrationListChanged": "serviceWorkerRegistrationList",
+  "tabNavigated": "tabNavigated",
+  "frameUpdate": "frameUpdate",
   "pageError": "pageError",
   "evaluationResult": "evaluationResult",
-  "updatedSource": "updatedSource",
-  "inspectObject": "inspectObject",
-
-  // newSource is still emitted on the ThreadActor, in addition to the
-  // BrowsingContextActor we have to keep it here until ThreadClient is converted to
-  // ThreadFront and/or we stop emitting this duplicated events.
-  // See ThreadActor.onNewSourceEvent.
   "newSource": "newSource",
+  "updatedSource": "updatedSource",
+  "inspectObject": "inspectObject"
 };
 
 /**
diff --git a/devtools/shared/client/debugger-client.js b/devtools/shared/client/debugger-client.js
index 8f781ea1427c..af15188bfdad 100644
--- a/devtools/shared/client/debugger-client.js
+++ b/devtools/shared/client/debugger-client.js
@@ -24,11 +24,10 @@ loader.lazyRequireGetter(this, "EventEmitter", "devtools/shared/event-emitter");
 loader.lazyRequireGetter(this, "WebConsoleClient", "devtools/shared/webconsole/client", true);
 loader.lazyRequireGetter(this, "AddonClient", "devtools/shared/client/addon-client");
 loader.lazyRequireGetter(this, "RootClient", "devtools/shared/client/root-client");
-loader.lazyRequireGetter(this, "BrowsingContextFront", "devtools/shared/fronts/targets/browsing-context", true);
+loader.lazyRequireGetter(this, "TabClient", "devtools/shared/client/tab-client");
 loader.lazyRequireGetter(this, "ThreadClient", "devtools/shared/client/thread-client");
 loader.lazyRequireGetter(this, "WorkerClient", "devtools/shared/client/worker-client");
 loader.lazyRequireGetter(this, "ObjectClient", "devtools/shared/client/object-client");
-loader.lazyRequireGetter(this, "Pool", "devtools/shared/protocol", true);
 
 // Retrieve the major platform version, i.e. if we are on Firefox 64.0a1, it will be 64.
 const PLATFORM_MAJOR_VERSION = AppConstants.MOZ_APP_VERSION.match(/\d+/)[0];
@@ -51,19 +50,8 @@ function DebuggerClient(transport) {
   this._transport.hooks = this;
 
   // Map actor ID to client instance for each actor type.
-  // To be removed once all clients are refactored to protocol.js
   this._clients = new Map();
 
-  // Pool of fronts instanciated by this class.
-  // This is useful for actors that have already been transitioned to protocol.js
-  // Once RootClient becomes a protocol.js actor, these actors can be attached to it
-  // instead of this pool.
-  // This Pool will automatically be added to this._pools via addActorPool once the first
-  // Front will be added to it (in attachTarget, attachWorker,...).
-  // And it does not need to destroyed explicitly as all Pools are destroyed on client
-  // closing.
-  this._frontPool = new Pool(this);
-
   this._pendingRequests = new Map();
   this._activeRequests = new Map();
   this._eventsEnabled = true;
@@ -296,9 +284,7 @@ DebuggerClient.prototype = {
     this._eventsEnabled = false;
 
     const cleanup = () => {
-      if (this._transport) {
-        this._transport.close();
-      }
+      this._transport.close();
       this._transport = null;
     };
 
@@ -368,15 +354,29 @@ DebuggerClient.prototype = {
    * @param string targetActor
    *        The target actor ID for the tab to attach.
    */
-  attachTarget: async function(targetActor) {
-    let front = this._frontPool.actor(targetActor);
-    if (!front) {
-      front = new BrowsingContextFront(this, { actor: targetActor });
-      this._frontPool.manage(front);
+  attachTarget: function(targetActor) {
+    if (this._clients.has(targetActor)) {
+      const cachedTarget = this._clients.get(targetActor);
+      const cachedResponse = {
+        cacheDisabled: cachedTarget.cacheDisabled,
+        javascriptEnabled: cachedTarget.javascriptEnabled,
+        traits: cachedTarget.traits,
+      };
+      return promise.resolve([cachedResponse, cachedTarget]);
     }
 
-    const response = await front.attach();
-    return [response, front];
+    const packet = {
+      to: targetActor,
+      type: "attach"
+    };
+    return this.request(packet).then(response => {
+      // TabClient can actually represent targets other than a tab.
+      // It is planned to be renamed while being converted to a front
+      // in bug 1485660.
+      const targetClient = new TabClient(this, response);
+      this.registerClient(targetClient);
+      return [response, targetClient];
+    });
   },
 
   attachWorker: function(workerTargetActor) {
diff --git a/devtools/shared/client/moz.build b/devtools/shared/client/moz.build
index 3fa90f38dc4b..a7b28a798437 100644
--- a/devtools/shared/client/moz.build
+++ b/devtools/shared/client/moz.build
@@ -19,6 +19,7 @@ DevToolsModules(
     'root-client.js',
     'source-client.js',
     'symbol-iterator-client.js',
+    'tab-client.js',
     'thread-client.js',
     'worker-client.js',
 )
diff --git a/devtools/shared/client/tab-client.js b/devtools/shared/client/tab-client.js
new file mode 100644
index 000000000000..0936853a7ae9
--- /dev/null
+++ b/devtools/shared/client/tab-client.js
@@ -0,0 +1,163 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const promise = require("devtools/shared/deprecated-sync-thenables");
+
+const eventSource = require("devtools/shared/client/event-source");
+const {arg, DebuggerClient} = require("devtools/shared/client/debugger-client");
+loader.lazyRequireGetter(this, "ThreadClient", "devtools/shared/client/thread-client");
+
+/**
+ * Creates a tab client for the remote debugging protocol server. This client is a front
+ * to the target actor for a tab created in the server side, hiding the protocol details
+ * in a traditional JavaScript API.
+ *
+ * @param client DebuggerClient
+ *        The debugger client parent.
+ * @param form object
+ *        The protocol form for this tab.
+ */
+function TabClient(client, form) {
+  this.client = client;
+  this._actor = form.from;
+  this._threadActor = form.threadActor;
+  this.javascriptEnabled = form.javascriptEnabled;
+  this.cacheDisabled = form.cacheDisabled;
+  this.thread = null;
+  this.request = this.client.request;
+  this.traits = form.traits || {};
+  this.events = ["workerListChanged"];
+}
+
+TabClient.prototype = {
+  get actor() {
+    return this._actor;
+  },
+  get _transport() {
+    return this.client._transport;
+  },
+
+  /**
+   * Attach to a thread actor.
+   *
+   * @param object options
+   *        Configuration options.
+   *        - useSourceMaps: whether to use source maps or not.
+   */
+  attachThread: function(options = {}) {
+    if (this.thread) {
+      return promise.resolve([{}, this.thread]);
+    }
+
+    const packet = {
+      to: this._threadActor,
+      type: "attach",
+      options,
+    };
+    return this.request(packet).then(response => {
+      this.thread = new ThreadClient(this, this._threadActor);
+      this.client.registerClient(this.thread);
+      return [response, this.thread];
+    });
+  },
+
+  /**
+   * Detach the client from the target actor.
+   */
+  detach: DebuggerClient.requester({
+    type: "detach"
+  }, {
+    before: function(packet) {
+      if (this.thread) {
+        this.thread.detach();
+      }
+      return packet;
+    },
+    after: function(response) {
+      this.client.unregisterClient(this);
+      return response;
+    },
+  }),
+
+  /**
+   * Bring the window to the front.
+   */
+  focus: DebuggerClient.requester({
+    type: "focus"
+  }, {}),
+
+  /**
+   * Ensure relevant pages have error reporting enabled.
+   */
+  ensureCSSErrorReportingEnabled: DebuggerClient.requester({
+    type: "ensureCSSErrorReportingEnabled",
+  }, {}),
+
+  /**
+   * Reload the page in this tab.
+   *
+   * @param [optional] object options
+   *        An object with a `force` property indicating whether or not
+   *        this reload should skip the cache
+   */
+  reload: function(options = { force: false }) {
+    return this._reload(options);
+  },
+  _reload: DebuggerClient.requester({
+    type: "reload",
+    options: arg(0)
+  }),
+
+  /**
+   * Navigate to another URL.
+   *
+   * @param string url
+   *        The URL to navigate to.
+   */
+  navigateTo: DebuggerClient.requester({
+    type: "navigateTo",
+    url: arg(0)
+  }),
+
+  /**
+   * Reconfigure the target actor.
+   *
+   * @param object options
+   *        A dictionary object of the new options to use in the target actor.
+   */
+  reconfigure: DebuggerClient.requester({
+    type: "reconfigure",
+    options: arg(0)
+  }),
+
+  listWorkers: DebuggerClient.requester({
+    type: "listWorkers"
+  }),
+
+  attachWorker: function(workerTargetActor) {
+    return this.client.attachWorker(workerTargetActor);
+  },
+
+  logInPage: DebuggerClient.requester({
+    type: "logInPage",
+    text: arg(0),
+    category: arg(1),
+    flags: arg(2),
+  }),
+
+  listFrames: DebuggerClient.requester({
+    type: "listFrames",
+  }),
+
+  switchToFrame: DebuggerClient.requester({
+    type: "switchToFrame",
+    windowId: arg(0),
+  }),
+};
+
+eventSource(TabClient.prototype);
+
+module.exports = TabClient;
diff --git a/devtools/shared/client/thread-client.js b/devtools/shared/client/thread-client.js
index 76b6e9e2a978..4c159bbf10bc 100644
--- a/devtools/shared/client/thread-client.js
+++ b/devtools/shared/client/thread-client.js
@@ -25,7 +25,7 @@ const noop = () => {};
  * is a front to the thread actor created in the server side, hiding the
  * protocol details in a traditional JavaScript API.
  *
- * @param client DebuggerClient, WorkerClient or BrowsingContextFront
+ * @param client DebuggerClient|TabClient
  *        The parent of the thread (tab for target-scoped debuggers,
  *        DebuggerClient for chrome debuggers).
  * @param actor string
diff --git a/devtools/shared/fronts/moz.build b/devtools/shared/fronts/moz.build
index 202b31344f97..3a02c4f9ede9 100644
--- a/devtools/shared/fronts/moz.build
+++ b/devtools/shared/fronts/moz.build
@@ -6,7 +6,6 @@
 
 DIRS += [
     'addon',
-    'targets',
 ]
 
 DevToolsModules(
diff --git a/devtools/shared/fronts/targets/browsing-context.js b/devtools/shared/fronts/targets/browsing-context.js
deleted file mode 100644
index 7a692b1cd6ed..000000000000
--- a/devtools/shared/fronts/targets/browsing-context.js
+++ /dev/null
@@ -1,88 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-"use strict";
-
-const {browsingContextTargetSpec} = require("devtools/shared/specs/targets/browsing-context");
-const protocol = require("devtools/shared/protocol");
-const {custom} = protocol;
-
-loader.lazyRequireGetter(this, "ThreadClient", "devtools/shared/client/thread-client");
-
-const BrowsingContextFront = protocol.FrontClassWithSpec(browsingContextTargetSpec, {
-  initialize: function(client, form) {
-    protocol.Front.prototype.initialize.call(this, client, form);
-
-    this.thread = null;
-
-    // TODO: remove once ThreadClient becomes a front
-    this.client = client;
-  },
-
-  /**
-   * Attach to a thread actor.
-   *
-   * @param object options
-   *        Configuration options.
-   *        - useSourceMaps: whether to use source maps or not.
-   */
-  attachThread: function(options = {}) {
-    if (this.thread) {
-      return Promise.resolve([{}, this.thread]);
-    }
-
-    const packet = {
-      to: this._threadActor,
-      type: "attach",
-      options,
-    };
-    return this.client.request(packet).then(response => {
-      this.thread = new ThreadClient(this, this._threadActor);
-      this.client.registerClient(this.thread);
-      return [response, this.thread];
-    });
-  },
-
-  attach: custom(async function() {
-    const response = await this._attach();
-
-    this._threadActor = response.threadActor;
-    this.javascriptEnabled = response.javascriptEnabled;
-    this.cacheDisabled = response.cacheDisabled;
-    this.traits = response.traits || {};
-
-    return response;
-  }, {
-    impl: "_attach"
-  }),
-
-  detach: custom(async function() {
-    let response;
-    try {
-      response = await this._detach();
-    } catch (e) {
-      console.warn(
-        `Error while detaching the browsing context target front: ${e.message}`);
-    }
-
-    if (this.thread) {
-      try {
-        await this.thread.detach();
-      } catch (e) {
-        console.warn(`Error while detaching the thread front: ${e.message}`);
-      }
-    }
-
-    this.destroy();
-
-    return response;
-  }, {
-    impl: "_detach"
-  }),
-
-  attachWorker: function(workerTargetActor) {
-    return this.client.attachWorker(workerTargetActor);
-  },
-});
-
-exports.BrowsingContextFront = BrowsingContextFront;
diff --git a/devtools/shared/fronts/targets/moz.build b/devtools/shared/fronts/targets/moz.build
deleted file mode 100644
index cd66f4e661c7..000000000000
--- a/devtools/shared/fronts/targets/moz.build
+++ /dev/null
@@ -1,9 +0,0 @@
-# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
-# vim: set filetype=python:
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this
-# file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-DevToolsModules(
-    'browsing-context.js',
-)
diff --git a/devtools/shared/protocol.js b/devtools/shared/protocol.js
index 338fb8eacd72..58dbeb4f6c4e 100644
--- a/devtools/shared/protocol.js
+++ b/devtools/shared/protocol.js
@@ -1352,10 +1352,7 @@ Front.prototype = extend(Pool.prototype, {
     } else {
       this.actor().then(actorID => {
         packet.to = actorID;
-        // The connection might be closed during the promise resolution
-        if (this.conn._transport) {
-          this.conn._transport.send(packet);
-        }
+        this.conn._transport.send(packet);
       }).catch(console.error);
     }
   },
diff --git a/devtools/shared/specs/targets/browsing-context.js b/devtools/shared/specs/targets/browsing-context.js
index 9d7c902a7837..02f6a6875662 100644
--- a/devtools/shared/specs/targets/browsing-context.js
+++ b/devtools/shared/specs/targets/browsing-context.js
@@ -127,17 +127,10 @@ const browsingContextTargetSpecPrototype = {
       destroyAll: Option(0, "nullable:boolean")
     },
     tabDetached: {
-      type: "tabDetached",
-      // This is to make browser_dbg_navigation.js to work as it expect to
-      // see a packet object when listening for tabDetached
-      from: Option(0, "string"),
+      type: "tabDetached"
     },
     workerListChanged: {
       type: "workerListChanged"
-    },
-    newSource: {
-      type: "newSource",
-      source: Option(0, "json")
     }
   }
 };