Bug 1630691: Part 2 - Get rid of the "dom.mozBrowserFramesEnabled" pref. r=nika

Differential Revision: https://phabricator.services.mozilla.com/D71227

browser/app/profile/firefox.js

@@ -1713,9 +1713,6 @@ pref("dom.ipc.processPrelaunch.enabled", true);
 pref("browser.migrate.chrome.history.limit", 2000);
 pref("browser.migrate.chrome.history.maxAgeInDays", 180);
 
-// Enable browser frames for use on desktop.  Only exposed to chrome callers.
-pref("dom.mozBrowserFramesEnabled", true);
-
 pref("extensions.pocket.api", "api.getpocket.com");
 pref("extensions.pocket.enabled", true);
 pref("extensions.pocket.oAuthConsumerKey", "40249-e88c401e1b1f2242d9e441c4");

dom/browser-element/BrowserElementPromptService.jsm

@@ -11,9 +11,6 @@ var EXPORTED_SYMBOLS = ["BrowserElementPromptService"];
 
 const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm");
 
-const NS_PREFBRANCH_PREFCHANGE_TOPIC_ID = "nsPref:changed";
-const BROWSER_FRAMES_ENABLED_PREF = "dom.mozBrowserFramesEnabled";
-
 function debug(msg) {
   // dump("BrowserElementPromptService - " + msg + "\n");
 }
@@ -648,16 +645,6 @@ var BrowserElementPromptService = {
       return;
     }
 
-    // If the pref is disabled, do nothing except wait for the pref to change.
-    if (!this._browserFramesPrefEnabled()) {
-      Services.prefs.addObserver(
-        BROWSER_FRAMES_ENABLED_PREF,
-        this,
-        /* ownsWeak = */ true
-      );
-      return;
-    }
-
     this._initialized = true;
     this._browserElementParentMap = new WeakMap();
 
@@ -734,17 +721,8 @@ var BrowserElementPromptService = {
     delete this._browserElementChildMap[outerWindowID.data];
   },
 
-  _browserFramesPrefEnabled() {
-    return Services.prefs.getBoolPref(BROWSER_FRAMES_ENABLED_PREF, false);
-  },
-
   observe(subject, topic, data) {
     switch (topic) {
-      case NS_PREFBRANCH_PREFCHANGE_TOPIC_ID:
-        if (data == BROWSER_FRAMES_ENABLED_PREF) {
-          this._init();
-        }
-        break;
       case "outer-window-destroyed":
         this._observeOuterWindowDestroyed(subject);
         break;

dom/html/nsGenericHTMLFrameElement.cpp

@@ -255,9 +255,8 @@ nsresult nsGenericHTMLFrameElement::AfterSetAttr(
         }
       }
     } else if (aName == nsGkAtoms::mozbrowser) {
-      mReallyIsBrowser =
+      mReallyIsBrowser = !!aValue && XRE_IsParentProcess() &&
-          !!aValue && StaticPrefs::dom_mozBrowserFramesEnabled() &&
+                         NodePrincipal()->IsSystemPrincipal();
-          XRE_IsParentProcess() && NodePrincipal()->IsSystemPrincipal();
     }
   }
 

modules/libpref/init/StaticPrefList.yaml

@@ -2084,12 +2084,6 @@
   value: true
   mirror: always
 
-# Is support for mozBrowser frames enabled?
-- name: dom.mozBrowserFramesEnabled
-  type: bool
-  value: false
-  mirror: always
-
 # Whether we disable triggering mutation events for changes to style
 # attribute via CSSOM.
 # NOTE: This preference is used in unit tests. If it is removed or its default