app_shell: Fix PrefsTabHelper dependency of ExtensionHost

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 "base/memory/scoped_ptr.h"
 
 class CommandLine;
 class PrefService;
 
 namespace content {
 class BrowserContext;
 class JavaScriptDialogManager;
+class WebContents;
 }
 
 namespace extensions {
 
 class AppSorting;
 
 // Interface to allow the extensions module to make browser-process-specific
 // queries of the embedder. Should be Set() once in the browser process.
 //
 // NOTE: Methods that do not require knowledge of browser concepts should be
@@ skipping 38 matching lines @@
   virtual PrefService* GetPrefServiceForContext(
       content::BrowserContext* context) = 0;
 
   // Returns true if loading background pages should be deferred.
   virtual bool DeferLoadingBackgroundHosts(
       content::BrowserContext* context) const = 0;
 
   virtual bool IsBackgroundPageAllowed(
       content::BrowserContext* context) const = 0;
 
+  // Called after the hosting |web_contents| for an extension is created. The
+  // implementation may wish to add preference observers to |web_contents|.
+  virtual void OnExtensionHostCreated(content::WebContents* web_contents) = 0;
+
   // Returns true if the client version has updated since the last run. Called
   // once each time the extensions system is loaded per browser_context. The
   // implementation may wish to use the BrowserContext to record the current
   // version for later comparison.
   virtual bool DidVersionUpdate(content::BrowserContext* context) = 0;
 
   // Creates a new AppSorting instance.
   virtual scoped_ptr<AppSorting> CreateAppSorting() = 0;
 
   // Return true if the system is run in forced app mode.
   virtual bool IsRunningInForcedAppMode() = 0;
 
   // Returns the embedder's JavaScriptDialogManager or NULL if the embedder
   // does not support JavaScript dialogs.
   virtual content::JavaScriptDialogManager* GetJavaScriptDialogManager() = 0;
 
   // 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_