Remove some TabContentses from extensions.

chrome/browser/extensions/api/offscreen_tabs/offscreen_tabs_api.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_EXTENSIONS_API_OFFSCREEN_TABS_OFFSCREEN_TABS_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_OFFSCREEN_TABS_OFFSCREEN_TABS_API_H_
 
 #include <string>
 
 #include "base/values.h"
 #include "chrome/browser/extensions/api/tabs/tabs.h"
 #include "chrome/browser/extensions/extension_function.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/web_contents_observer.h"
 
 // The offscreen tabs module depends on the tabs module so we can share
 // code between them. The long-term goal is to fold the offscreen tabs
 // functionality into the tabs API. While these methods seem very similar to
 // those in tabs, there are a few key differences that need to be resolved.
 //  - Offscreen tabs are invisible (maybe this could be a property on Tab).
 //  - The lifetime of an offscreen tab is tied to the parent tab that opened
 //    it. We do this to prevent leaking these tabs, since users wouldn't have
 //    a way of directly closing them or knowing they're open.
 //  - Offscreen tabs have a width and height, while regular tabs don't. This
 //    lets clients control the dimensions of the images in ToDataUrl.
 
 class BackingStore;
 class SkBitmap;
-class TabContents;
+
 namespace content {
 class WebContents;
-}  // namespace content
+}
 
 // Creates an offscreen tab.
 class CreateOffscreenTabFunction : public SyncExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION_NAME("experimental.offscreenTabs.create")
 
   CreateOffscreenTabFunction();
 
  protected:
   virtual ~CreateOffscreenTabFunction();
@@ skipping 127 matching lines @@
   virtual bool RunImpl() OVERRIDE;
 
   // UpdateTabFunction:
   virtual void PopulateResult() OVERRIDE;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(UpdateOffscreenTabFunction);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_OFFSCREEN_TABS_OFFSCREEN_TABS_API_H_