chrome/renderer/prerender/prerender_helper.h

// Copyright (c) 2011 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_RENDERER_PRERENDER_PRERENDER_HELPER_H_
#define CHROME_RENDERER_PRERENDER_PRERENDER_HELPER_H_

#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/time/time.h"
#include "chrome/common/prerender_types.h"
#include "content/public/renderer/render_frame_observer.h"
#include "content/public/renderer/render_frame_observer_tracker.h"

namespace prerender {
class PrerenderURLLoaderThrottle;

// Helper class to track whether its RenderFrame is currently being prerendered.
// Created when prerendering starts and deleted as soon as it stops.
class PrerenderHelper
    : public content::RenderFrameObserver,
      public content::RenderFrameObserverTracker<PrerenderHelper> {
 public:
  PrerenderHelper(content::RenderFrame* render_frame,
                  PrerenderMode prerender_mode,
                  const std::string& histogram_prefix);

  ~PrerenderHelper() override;

  // Called when a PrerenderURLLoaderThrottle is created for a resource for
  // this frame.
  void AddThrottle(const base::WeakPtr<PrerenderURLLoaderThrottle>& throttle);

  PrerenderMode prerender_mode() const { return prerender_mode_; }
  std::string histogram_prefix() const { return histogram_prefix_; }

  // Returns true if |render_view| is currently prerendering.
  static bool IsPrerendering(const content::RenderFrame* render_frame);

  static PrerenderMode GetPrerenderMode(
      const content::RenderFrame* render_frame);

 private:
  // RenderFrameObserver implementation.
  bool OnMessageReceived(const IPC::Message& message) override;
  void OnDestruct() override;

  void OnSetIsPrerendering(PrerenderMode mode,
                           const std::string& histogram_prefix);

  PrerenderMode prerender_mode_;
  std::string histogram_prefix_;

  // Pending requests for this frame..
  std::vector<base::WeakPtr<PrerenderURLLoaderThrottle>> throttles_;

  DISALLOW_COPY_AND_ASSIGN(PrerenderHelper);
};

}  // namespace prerender

#endif  // CHROME_RENDERER_PRERENDER_PRERENDER_HELPER_H_