Remote Assistance on Chrome OS Part I - Aura Desktop Capturer

remoting/host/chromeos/aura_desktop_capturer.h

+// Copyright 2014 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 REMOTING_HOST_CHROMEOS_AURA_DESKTOP_CAPTURER_H_
+#define REMOTING_HOST_CHROMEOS_AURA_DESKTOP_CAPTURER_H_
+
+#include "third_party/webrtc/modules/desktop_capture/screen_capturer.h"
+#include "ui/aura/window.h"
+
+namespace cc {
+class CopyOutputResult;
+}  // namespace
+
+namespace remoting {
+
+// A webrtc desktop capturer that captures pixels from the root window of the

[Sergey Ulanov, 2014/09/06 02:03:25]

s/webrtc desktop capturer/webrtc::DesktopCapturer/

[kelvinp, 2014/09/09 21:19:46]

Done.

+// Aura Shell.
+class AuraDesktopCapturer : public webrtc::DesktopCapturer {
+ public:
+  AuraDesktopCapturer();
+  virtual ~AuraDesktopCapturer();
+
+  // Called at the beginning of a capturing session. |callback| must remain

[Sergey Ulanov, 2014/09/06 02:03:25]

This duplicates comments from the interface definition. For overridden
interfaces it's enough to have the following comment
  // webrtc::DesktopCapturer implementation.

All interesting details specific to this particular implementation can go to the
class description.

[kelvinp, 2014/09/09 21:19:46]

Done.

+  // valid until capturer is destroyed.  Must be called on the browser UI

[Sergey Ulanov, 2014/09/06 02:03:25]

This doesn't look right. normally we use DesktopCapturer on the capturer thread.
In this case I think the implementation will need to jump to jump between the
capturer and UI thread. Or do you plan to map capturer thread to the UI thread
in case of ChromeOS?

[kelvinp, 2014/09/09 21:19:46]

Yes, the capturer thread will be mapped to the UI thread in the case of
ChromeOS.

+  // thread.
+  virtual void Start(webrtc::DesktopCapturer::Callback* callback) OVERRIDE;
+
+  // Captures the next frame. In Aura, this is implemented by requesting the
+  // layer and its substree to be rendered to a given data structure. |region|
+  // specifies region of the capture target that should be fresh in the
+  // resulting frame. Since Aura doesn't support partial capturing, the entire
+  // region of the captured frame will always be fresh. Pending capture
+  // operations are cancelled when DesktopCapturer is deleted.
+  virtual void Capture(const webrtc::DesktopRegion& region) OVERRIDE;
+
+  // Sets the window to be excluded from the captured image in the future
+  // Capture calls. Not supported in Aura.
+  virtual void SetExcludedWindow(webrtc::WindowId window) OVERRIDE {}
+
+ private:
+  // Called when a copy of the layer is captured.
+  void OnFrameCaptured(scoped_ptr<cc::CopyOutputResult> result);
+
+  // Points to the callback passed to webrtc::DesktopCapturer::Start().
+  webrtc::DesktopCapturer::Callback* callback_;
+
+  // The root window of the Aura Shell.
+  aura::Window* desktop_window_;
+
+  base::WeakPtrFactory<AuraDesktopCapturer> weak_factory_;
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_CHROMEOS_AURA_DESKTOP_CAPTURER_H_