Bug 1562740 - Input:dispatchKeyEvent should wait for events in content process r=remote-protocol-reviewers,ochameau

Depends on D37165

Differential Revision: https://phabricator.services.mozilla.com/D37166

--HG--
extra : moz-landing-system : lando

remote/domains/content/Input.jsm

@@ -10,4 +10,47 @@ const { ContentProcessDomain } = ChromeUtils.import(
   "chrome://remote/content/domains/ContentProcessDomain.jsm"
 );
 
-class Input extends ContentProcessDomain {}
+class Input extends ContentProcessDomain {
+  constructor(session) {
+    super(session);
+
+    // Map of event name -> event handler promise.
+    this._eventPromises = new Map();
+  }
+
+  /**
+   * Not a CDP method.
+   *
+   * Add an event listener in the content page for the provided eventName.
+   * To wait for the event, you should use `waitForContentEvent` with the same event name.
+   *
+   * Example usage from a parent process domain:
+   *
+   *   await this.executeInChild("addContentEventListener", "click");
+   *   // do something that triggers a click in content
+   *   await this.executeInChild("waitForContentEvent", "click");
+   */
+  addContentEventListener(eventName) {
+    const eventPromise = new Promise(r => {
+      this.chromeEventHandler.addEventListener(eventName, r, {
+        mozSystemGroup: true,
+        once: true,
+      });
+    });
+    this._eventPromises.set(eventName, eventPromise);
+  }
+
+  /**
+   * Not a CDP method.
+   *
+   * Wait for an event listener added via `addContentEventListener` to be fired.
+   */
+  async waitForContentEvent(eventName) {
+    const eventPromise = this._eventPromises.get(eventName);
+    if (!eventPromise) {
+      throw new Error("No event promise available for " + eventName);
+    }
+    await eventPromise;
+    this._eventPromises.delete(eventName);
+  }
+}

remote/domains/parent/Input.jsm

@@ -50,12 +50,7 @@ class Input extends Domain {
     const browserWindow = browser.ownerGlobal;
 
     const EventUtils = this._getEventUtils(browserWindow);
-    const onEvent = new Promise(r => {
-      browserWindow.addEventListener(domType, r, {
-        mozSystemGroup: true,
-        once: true,
-      });
-    });
+    await this.executeInChild("addContentEventListener", domType);
 
     if (type == "char") {
       // type == "char" is used when doing `await page.keyboard.type( 'I’m a list' );`
@@ -77,7 +72,8 @@ class Input extends Domain {
         browserWindow
       );
     }
-    await onEvent;
+
+    await this.executeInChild("waitForContentEvent", domType);
   }
 
   async dispatchMouseEvent({ type, button, x, y, modifiers, clickCount }) {