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// 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_
#pragma once
#include "base/compiler_specific.h"
#include "base/time.h"
#include "content/public/renderer/render_view_observer.h"
#include "content/public/renderer/render_view_observer_tracker.h"
namespace prerender {
// Helper class to track whether its RenderView is currently being prerendered.
// Also records prerendering-related histograms information and cancels
// prerendering when necessary, based on observed events. Created when
// prerendering starts and deleted as soon as just after the prerendering
// histograms have been recorded for a displayed prerendered page. For
// non-displayed pages, deleted on destruction of the RenderView.
class PrerenderHelper
: public content::RenderViewObserver,
public content::RenderViewObserverTracker<PrerenderHelper> {
public:
explicit PrerenderHelper(content::RenderView* render_view);
virtual ~PrerenderHelper();
// Returns true if |render_view| is currently prerendering.
static bool IsPrerendering(const content::RenderView* render_view);
// Records prerender histograms. These are recorded even for pages that are
// not prerendered, for comparison to pages that are.
static void RecordHistograms(
content::RenderView* render_view,
const base::Time& finish_all_loads,
const base::TimeDelta& begin_to_finish_all_loads);
private:
// RenderViewObserver implementation
virtual void DidStartProvisionalLoad(WebKit::WebFrame* frame) OVERRIDE;
virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
void OnSetIsPrerendering(bool is_prerendering);
// Returns true if the page is no longer being prerendered, but no histograms
// for the prerender have been recorded.
bool HasUnrecordedData() const;
// Updates the visibility state of the RenderView. Must be called whenever
// prerendering starts or finishes.
void UpdateVisibilityState();
// Tracks whether or not observed RenderView is currently prerendering.
bool is_prerendering_;
// Time when the prerender started.
base::Time prerender_start_time_;
// Time when the prerendered page was displayed.
base::Time prerender_display_time_;
// Set to true when a prerendered page is displayed to prevent deletion from
// when a prerendered page is displayed until after the histograms for the
// page load have been recorded.
bool has_unrecorded_data_;
DISALLOW_COPY_AND_ASSIGN(PrerenderHelper);
};
} // namespace prerender
#endif // CHROME_RENDERER_PRERENDER_PRERENDER_HELPER_H_
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