Bug 1561844 Remove OpenH264 plugin from about:addons r=VladBaicu

Removed OpenH264 plugin from addons list for users that doesn't have it installed.

Differential Revision: https://phabricator.services.mozilla.com/D37237

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

mobile/android/chrome/content/browser.js

@@ -230,6 +230,8 @@ ChromeUtils.defineModuleGetter(
   "resource://gre/modules/ContentBlockingAllowList.jsm"
 );
 
+ChromeUtils.defineModuleGetter(this, "GMPInstallManager", "resource://gre/modules/GMPInstallManager.jsm");
+
 var GlobalEventDispatcher = EventDispatcher.instance;
 var WindowEventDispatcher = EventDispatcher.for(window);
 
@@ -679,6 +681,8 @@ var BrowserApp = {
       Services.prefs.setBoolPref("xpinstall.enabled", true);
     }
 
+    this.hideH264AddonIfNeeded();
+
     if (ParentalControls.parentalControlsEnabled) {
       let isBlockListEnabled = ParentalControls.isAllowed(
         ParentalControls.BLOCK_LIST
@@ -848,6 +852,20 @@ var BrowserApp = {
     WindowEventDispatcher.sendRequest({ type: "Locale:Set", locale: locale });
   },
 
+  hideH264AddonIfNeeded: function() {
+    let installManager = new GMPInstallManager();
+    installManager.checkForAddons().then(({usedFallback, gmpAddons}) => {
+      gmpAddons.forEach((addon) => {
+        if (addon && addon.id === 'gmp-gmpopenh264' && !addon.isInstalled) {
+          Services.prefs.setBoolPref('media.gmp-gmpopenh264.visible', false);
+          Services.prefs.setBoolPref('media.gmp-gmpopenh264.enabled', false);
+        }
+      });
+    }, (err) => {
+      console.log(`Checking for addons failed with:${err}`);
+    });
+  },
+
   initContextMenu: function() {
     // We pass a thunk in place of a raw label string. This allows the
     // context menu to automatically accommodate locale changes without