Bug 1599806 - avoid AccessibilityFront's bootstrap method by renaming it into initialize. Do not explicitly destroy accessibility walker front and let accessibility actor manage its lifecycle fully. r=ochameau

Differential Revision: https://phabricator.services.mozilla.com/D58027

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

devtools/client/accessibility/accessibility-startup.js

@@ -30,22 +30,16 @@ class AccessibilityStartup {
   }
 
   get walker() {
-    return this._walker;
+    return this._accessibility.accessibleWalkerFront;
   }
 
   /**
-   * Determine which features are supported based on the version of the server. Also, sync
-   * the state of the accessibility front/actor.
+   * Determine which features are supported based on the version of the server.
    * @return {Promise}
-   *         A promise that returns true when accessibility front is fully in sync with
-   *         the actor.
+   *         A promise that returns true when accessibility front is ready.
    */
   async prepareAccessibility() {
-    // We must call a method on an accessibility front here (such as getWalker), in
-    // oreder to be able to check actor's backward compatibility via actorHasMethod.
-    // See targe.js@getActorDescription for more information.
     try {
-      this._walker = await this._accessibility.getWalker();
       this._supports = {};
       // To add a check for backward compatibility add something similar to the
       // example below:
@@ -54,9 +48,6 @@ class AccessibilityStartup {
       //   // Please specify the version of Firefox when the feature was added.
       //   this.target.actorHasMethod("accessibility", "getSimulator"),
       // ]);
-
-      await this._accessibility.bootstrap();
-
       return true;
     } catch (e) {
       // toolbox may be destroyed during this step.
@@ -124,9 +115,7 @@ class AccessibilityStartup {
       this._accessibility.off("init", this._updateToolHighlight);
       this._accessibility.off("shutdown", this._updateToolHighlight);
 
-      await this._walker.destroy();
       this._accessibility = null;
-      this._walker = null;
     }.bind(this)();
     return this._destroyingAccessibility;
   }

devtools/server/tests/browser/browser_accessibility_simple.js

@@ -35,8 +35,14 @@ add_task(async function() {
   ok(accessibility.getWalker, "The getWalker method exists");
   ok(accessibility.getSimulator, "The getSimulator method exists");
 
+  ok(accessibility.accessibleWalkerFront, "Accessible walker was initialized");
+
   let a11yWalker = await accessibility.getWalker();
-  ok(a11yWalker, "The AccessibleWalkerFront was returned");
+  is(
+    a11yWalker,
+    accessibility.accessibleWalkerFront,
+    "The AccessibleWalkerFront was returned"
+  );
 
   const a11ySimulator = await accessibility.getSimulator();
   const webRenderEnabled = isWebRenderEnabled(window);

devtools/server/tests/browser/head.js

@@ -86,8 +86,6 @@ async function initAccessibilityFrontForUrl(url) {
   const walker = inspector.walker;
   const accessibility = await target.getFront("accessibility");
 
-  await accessibility.bootstrap();
-
   return { inspector, walker, accessibility, target };
 }
 

devtools/shared/fronts/accessibility.js

@@ -187,12 +187,17 @@ class AccessibilityFront extends FrontClassWithSpec(accessibilitySpec) {
     this.formAttributeName = "accessibilityActor";
   }
 
-  bootstrap() {
-    return super.bootstrap().then(state => {
-      this.enabled = state.enabled;
-      this.canBeEnabled = state.canBeEnabled;
-      this.canBeDisabled = state.canBeDisabled;
-    });
+  async initialize() {
+    this.accessibleWalkerFront = await super.getWalker();
+    ({
+      enabled: this.enabled,
+      canBeEnabled: this.canBeEnabled,
+      canBeDisabled: this.canBeDisabled,
+    } = await this.bootstrap());
+  }
+
+  async getWalker() {
+    return this.accessibleWalkerFront;
   }
 
   init() {