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// Copyright (c) 2013 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.
//
// Given a starting render_process_id and render_view_id, the WebContentsTracker
// tracks RenderViewHost instance swapping during the lifetime of a WebContents
// instance. This is used when mirroring tab video and audio so that user
// navigations, crashes, etc., during a tab's lifetime allow the capturing code
// to remain active on the current/latest RenderView.
//
// Threading issues: Start(), Stop() and the ChangeCallback are invoked on the
// same thread. This can be any thread, and the decision is locked-in by
// WebContentsTracker when Start() is called.
#ifndef CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_TRACKER_H_
#define CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_TRACKER_H_
#include "base/callback.h"
#include "base/memory/ref_counted.h"
#include "content/common/content_export.h"
#include "content/public/browser/web_contents_observer.h"
namespace base {
class MessageLoopProxy;
}
namespace content {
class CONTENT_EXPORT WebContentsTracker
: public base::RefCountedThreadSafe<WebContentsTracker>,
public WebContentsObserver {
public:
WebContentsTracker();
// Callback for whenever the target is swapped. The callback is also invoked
// with both arguments set to MSG_ROUTING_NONE to indicate tracking will not
// continue (i.e., the WebContents instance was not found or has been
// destroyed).
typedef base::Callback<void(int render_process_id, int render_view_id)>
ChangeCallback;
// Start tracking. The last-known |render_process_id| and |render_view_id|
// are provided, and the given callback is invoked asynchronously one or more
// times. The callback will be invoked on the same thread calling Start().
virtual void Start(int render_process_id, int render_view_id,
const ChangeCallback& callback);
// Stop tracking. Once this method returns, the callback is guaranteed not to
// be invoked again.
virtual void Stop();
protected:
friend class base::RefCountedThreadSafe<WebContentsTracker>;
virtual ~WebContentsTracker();
private:
// Reads the render_process_id/render_view_id from the current WebContents
// instance and then invokes the callback.
void OnWebContentsChangeEvent();
// Called on the thread that Start()/Stop() are called on, check whether the
// callback is still valid and, if so, invoke it.
void MaybeDoCallback(int render_process_id, int render_view_id);
// Look-up the current WebContents instance associated with the given
// |render_process_id| and |render_view_id| and begin observing it.
void LookUpAndObserveWebContents(int render_process_id,
int render_view_id);
// WebContentsObserver overrides to react to events of interest.
virtual void RenderViewReady() OVERRIDE;
virtual void AboutToNavigateRenderView(RenderViewHost* render_view_host)
OVERRIDE;
virtual void DidNavigateMainFrame(const LoadCommittedDetails& details,
const FrameNavigateParams& params) OVERRIDE;
virtual void WebContentsDestroyed(WebContents* web_contents) OVERRIDE;
scoped_refptr<base::MessageLoopProxy> message_loop_;
ChangeCallback callback_;
DISALLOW_COPY_AND_ASSIGN(WebContentsTracker);
};
} // namespace content
#endif // CONTENT_BROWSER_RENDERER_HOST_MEDIA_WEB_CONTENTS_TRACKER_H_
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