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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 main_render_frame_id, the
// WebContentsTracker tracks changes to the active RenderFrameHost tree during
// the lifetime of a WebContents instance. This is used when mirroring tab
// video and audio so that user navigations, crashes, iframes, etc., during a
// tab's lifetime allow the capturing code to remain active on the
// current/latest render frame tree.
//
// 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_MEDIA_CAPTURE_WEB_CONTENTS_TRACKER_H_
#define CONTENT_BROWSER_MEDIA_CAPTURE_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 RenderWidgetHost;
class CONTENT_EXPORT WebContentsTracker
: public base::RefCountedThreadSafe<WebContentsTracker>,
public WebContentsObserver {
public:
// If |track_fullscreen_rwh| is true, the ChangeCallback will be run when a
// WebContents shows/destroys a fullscreen RenderWidgetHost view. If false,
// fullscreen events are ignored. Specify true for video tab capture and
// false for audio tab capture.
explicit WebContentsTracker(bool track_fullscreen_rwh);
// Callback to indicate a new RenderWidgetHost should be targeted for capture.
// This is also invoked with NULL to indicate tracking will not continue
// (i.e., the WebContents instance was not found or has been destroyed).
typedef base::Callback<void(RenderWidgetHost* rwh)> ChangeCallback;
// Start tracking. The last-known |render_process_id| and
// |main_render_frame_id| are provided, and |callback| will be run once to
// indicate the current capture target (this may occur during the invocation
// of Start(), or in the future). The callback will be invoked on the same
// thread calling Start().
virtual void Start(int render_process_id, int main_render_frame_id,
const ChangeCallback& callback);
// Stop tracking. Once this method returns, the callback is guaranteed not to
// be invoked again.
virtual void Stop();
// Current target. This must only be called on the UI BrowserThread.
RenderWidgetHost* GetTargetRenderWidgetHost() const;
protected:
friend class base::RefCountedThreadSafe<WebContentsTracker>;
~WebContentsTracker() override;
private:
// Determine the target RenderWidgetHost and, if different from that last
// reported, runs the ChangeCallback on the appropriate thread. If
// |force_callback_run| is true, the ChangeCallback is run even if the
// RenderWidgetHost has not changed.
void OnPossibleTargetChange(bool force_callback_run);
// Called on the thread that Start()/Stop() are called on. Checks whether the
// callback is still valid and, if so, runs it.
void MaybeDoCallback(RenderWidgetHost* rwh);
// Look-up the current WebContents instance associated with the given
// |render_process_id| and |main_render_frame_id| and begin observing it.
void StartObservingWebContents(int render_process_id,
int main_render_frame_id);
// WebContentsObserver overrides: According to web_contents_observer.h, these
// two method overrides are all that is necessary to track the set of active
// RenderFrameHosts.
void RenderFrameDeleted(RenderFrameHost* render_frame_host) override;
void RenderFrameHostChanged(RenderFrameHost* old_host,
RenderFrameHost* new_host) override;
// WebContentsObserver override to notify the client that the capture target
// has been permanently lost.
void WebContentsDestroyed() override;
// WebContentsObserver overrides to notify the client that the capture target
// may have changed due to a separate fullscreen widget shown/destroyed.
void DidShowFullscreenWidget(int routing_id) override;
void DidDestroyFullscreenWidget(int routing_id) override;
// If true, the client is interested in the showing/destruction of fullscreen
// RenderWidgetHosts.
const bool track_fullscreen_rwh_;
// MessageLoop corresponding to the thread that called Start().
scoped_refptr<base::MessageLoopProxy> message_loop_;
// Callback to run when the target RenderWidgetHost has changed.
ChangeCallback callback_;
// Pointer to the RenderWidgetHost provided in the last run of |callback_|.
// This is used to eliminate duplicate callback runs.
RenderWidgetHost* last_target_;
DISALLOW_COPY_AND_ASSIGN(WebContentsTracker);
};
} // namespace content
#endif // CONTENT_BROWSER_MEDIA_CAPTURE_WEB_CONTENTS_TRACKER_H_
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