Move ExtensionHost into extensions namespace

chrome/browser/ui/app_modal_dialogs/javascript_dialog_creator.h

 // Copyright (c) 2012 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 CHROME_BROWSER_UI_APP_MODAL_DIALOGS_JAVASCRIPT_DIALOG_CREATOR_H_
 #define CHROME_BROWSER_UI_APP_MODAL_DIALOGS_JAVASCRIPT_DIALOG_CREATOR_H_
 
 namespace content {
 class JavaScriptDialogCreator;
 }
 
+namespace extensions {
 class ExtensionHost;
+}
 
 // Returns a JavaScriptDialogCreator that creates real dialogs.
 // It returns a Singleton instance of JavaScriptDialogCreator,
 // which should not be deleted.
 content::JavaScriptDialogCreator* GetJavaScriptDialogCreatorInstance();
 
 // Creates and returns a JavaScriptDialogCreator owned by |extension_host|.
 // This is not the Singleton instance, so the caller must delete it.
 content::JavaScriptDialogCreator* CreateJavaScriptDialogCreatorInstance(
-    ExtensionHost* extension_host);
+    extensions::ExtensionHost* extension_host);
 
 #endif  // CHROME_BROWSER_UI_APP_MODAL_DIALOGS_JAVASCRIPT_DIALOG_CREATOR_H_