Cleanup: Remove NOTIFICATION_EXTENSION_UNLOADED usage in MediaScanManager.

extensions/browser/extension_registry.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef EXTENSIONS_BROWSER_EXTENSION_REGISTRY_H_
 #define EXTENSIONS_BROWSER_EXTENSION_REGISTRY_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
@@ skipping 18 matching lines @@
   // Flags to pass to GetExtensionById() to select which sets to look in.
   enum IncludeFlag {
     NONE        = 0,
     ENABLED     = 1 << 0,
     DISABLED    = 1 << 1,
     TERMINATED  = 1 << 2,
     BLACKLISTED = 1 << 3,
     EVERYTHING = (1 << 4) - 1,
   };
 
-  ExtensionRegistry();
+  explicit ExtensionRegistry(content::BrowserContext* browser_context);
   virtual ~ExtensionRegistry();
 
   // Returns the instance for the given |browser_context|.
   static ExtensionRegistry* Get(content::BrowserContext* browser_context);
 
   // NOTE: These sets are *eventually* mututally exclusive, but an extension can
   // appear in two sets for short periods of time.
   const ExtensionSet& enabled_extensions() const {
     return enabled_extensions_;
   }
@@ skipping 80 matching lines @@
   ExtensionSet terminated_extensions_;
 
   // Extensions that are installed and blacklisted. Generally these shouldn't be
   // considered as installed by the extension platform: we only keep them around
   // so that if extensions are blacklisted by mistake they can easily be
   // un-blacklisted.
   ExtensionSet blacklisted_extensions_;
 
   ObserverList<ExtensionRegistryObserver> observers_;
 
+  content::BrowserContext* const browser_context_;
+
   DISALLOW_COPY_AND_ASSIGN(ExtensionRegistry);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_EXTENSION_REGISTRY_H_