Bug 1602075 - add an accessibility-panel-auto-init feature to control the panel auto enabling functionality. r=mythmon,mtigley

Differential Revision: https://phabricator.services.mozilla.com/D71582

browser/app/profile/firefox.js

@@ -2135,6 +2135,11 @@ pref("devtools.dom.enabled", false);
 
 // Enable the Accessibility panel.
 pref("devtools.accessibility.enabled", true);
+#if defined(NIGHTLY_BUILD)
+  pref("devtools.accessibility.auto-init.enabled", true);
+#else
+  pref("devtools.accessibility.auto-init.enabled", false);
+#endif
 
 // Web console filters
 pref("devtools.webconsole.filter.error", true);

devtools/client/accessibility/accessibility-proxy.js

@@ -14,6 +14,12 @@ const PARENT_ACCESSIBILITY_EVENTS = [
   "can-be-enabled-change",
 ];
 
+loader.lazyImporter(
+  this,
+  "FeatureGate",
+  "resource://featuregates/FeatureGate.jsm"
+);
+
 /**
  * Component responsible for tracking all Accessibility fronts in parent and
  * content processes.
@@ -24,6 +30,7 @@ class AccessibilityProxy {
 
     this.accessibilityEventsMap = new Map();
     this.accessibleWalkerEventsMap = new Map();
+    this.supports = {};
 
     this.audit = this.audit.bind(this);
     this.disableAccessibility = this.disableAccessibility.bind(this);
@@ -250,12 +257,23 @@ class AccessibilityProxy {
     }
   }
 
+  async onChange(isEnabled) {
+    this.supports.autoInit = isEnabled;
+  }
+
   async initialize() {
     try {
       await this.toolbox.targetList.watchTargets(
         [this.toolbox.targetList.TYPES.FRAME],
         this._onTargetAvailable
       );
+      // Bug 1602075: auto init feature definition is used for an experiment to
+      // determine if we can automatically enable accessibility panel when it
+      // opens.
+      this.supports.autoInit = await FeatureGate.addObserver(
+        "accessibility-panel-auto-init",
+        this
+      );
       return true;
     } catch (e) {
       // toolbox may be destroyed during this step.
@@ -263,12 +281,14 @@ class AccessibilityProxy {
     }
   }
 
-  destroy() {
+  async destroy() {
     this.toolbox.targetList.unwatchTargets(
       [this.toolbox.targetList.TYPES.FRAME],
       this._onTargetAvailable
     );
 
+    await FeatureGate.removeObserver("accessibility-panel-auto-init", this);
+
     this.accessibilityEventsMap = null;
     this.accessibleWalkerEventsMap = null;
 
@@ -342,7 +362,6 @@ class AccessibilityProxy {
       // Finalize accessibility front initialization. See accessibility front
       // bootstrap method description.
       await this.accessibilityFront.bootstrap();
-      this.supports = {};
       // To add a check for backward compatibility add something similar to the
       // example below:
       //

devtools/client/accessibility/accessibility-startup.js

@@ -85,7 +85,7 @@ class AccessibilityStartup {
         shutdown: this._updateToolHighlight,
       });
 
-      this.accessibilityProxy.destroy();
+      await this.accessibilityProxy.destroy();
       this.accessibilityProxy = null;
     }.bind(this)();
     return this._destroyingAccessibility;

toolkit/components/featuregates/Features.toml

@@ -1,4 +1,3 @@
-# there are currently no feature gates
 [demo-feature]
 title = "Demo Feature"
 description = "A no-op feature to demo the feature gate system."
@@ -8,3 +7,12 @@ type = "boolean"
 bug-numbers = [1479127]
 is-public = true
 default-value = false
+
+[accessibility-panel-auto-init]
+title = "Accessibility Panel Automatic Initialization"
+description = "Automatically enables accessibility panel when it is opened."
+restart-required = false
+preference = "devtools.accessibility.auto-init.enabled"
+bug-numbers = [1602075]
+type = "boolean"
+default-value = {default = false, nightly = true}