Add extensions code to use common updater in components/update_client/

extensions/browser/extensions_browser_client.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_EXTENSIONS_BROWSER_CLIENT_H_
 #define EXTENSIONS_BROWSER_EXTENSIONS_BROWSER_CLIENT_H_
 
 #include <string>
 #include <vector>
 
+#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "extensions/browser/extension_event_histogram_value.h"
 #include "extensions/browser/extension_prefs_observer.h"
 #include "extensions/common/view_type.h"
 
 class ExtensionFunctionRegistry;
 class PrefService;
 
 namespace base {
 class CommandLine;
 class FilePath;
 class ListValue;
 }
 
 namespace content {
 class BrowserContext;
 class RenderFrameHost;
 class WebContents;
 }
 
 namespace net {
 class NetLog;
 class NetworkDelegate;
 class URLRequest;
 class URLRequestJob;
 }
 
+namespace update_client {
+class UpdateClient;
+}
+
 namespace extensions {
 
 class ApiActivityMonitor;
 class ComponentExtensionResourceManager;
 class Extension;
 class ExtensionCache;
 class ExtensionError;
 class ExtensionHostDelegate;
 class ExtensionPrefsObserver;
 class ExtensionSystem;
@@ skipping 178 matching lines @@
   virtual void CleanUpWebView(content::BrowserContext* browser_context,
                               int embedder_process_id,
                               int view_instance_id) {}
 
   // Attaches the task manager extension tag to |web_contents|, if needed based
   // on |view_type|, so that its corresponding task shows up in the task
   // manager.
   virtual void AttachExtensionTaskManagerTag(content::WebContents* web_contents,
                                              ViewType view_type) {}
 
+  // Returns a new UpdateClient.
+  virtual scoped_refptr<update_client::UpdateClient> CreateUpdateClient(
+      content::BrowserContext* context);
+
   // Returns the single instance of |this|.
   static ExtensionsBrowserClient* Get();
 
   // Initialize the single instance.
   static void Set(ExtensionsBrowserClient* client);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_EXTENSIONS_BROWSER_CLIENT_H_