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      1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef CHROME_RENDERER_PRERENDER_PRERENDER_HELPER_H_
      6 #define CHROME_RENDERER_PRERENDER_PRERENDER_HELPER_H_
      7 
      8 #include "base/compiler_specific.h"
      9 #include "base/time/time.h"
     10 #include "content/public/renderer/render_frame_observer.h"
     11 #include "content/public/renderer/render_frame_observer_tracker.h"
     12 
     13 namespace prerender {
     14 
     15 // Helper class to track whether its RenderFrame is currently being prerendered.
     16 // Created when prerendering starts and deleted as soon as it stops.
     17 class PrerenderHelper
     18     : public content::RenderFrameObserver,
     19       public content::RenderFrameObserverTracker<PrerenderHelper> {
     20  public:
     21   explicit PrerenderHelper(content::RenderFrame* render_frame);
     22   virtual ~PrerenderHelper();
     23 
     24   // Returns true if |render_view| is currently prerendering.
     25   static bool IsPrerendering(const content::RenderFrame* render_frame);
     26 
     27  private:
     28   // RenderViewObserver implementation
     29   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
     30 
     31   void OnSetIsPrerendering(bool is_prerendering);
     32 
     33   DISALLOW_COPY_AND_ASSIGN(PrerenderHelper);
     34 };
     35 
     36 }  // namespace prerender
     37 
     38 #endif  // CHROME_RENDERER_PRERENDER_PRERENDER_HELPER_H_
     39