Screen Video Capture: Implement suspend optimization.

content/browser/media/capture/aura_window_capture_machine.h

 // Copyright 2015 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 CONTENT_BROWSER_MEDIA_CAPTURE_AURA_WINDOW_CAPTURE_MACHINE_H_
 #define CONTENT_BROWSER_MEDIA_CAPTURE_AURA_WINDOW_CAPTURE_MACHINE_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 25 matching lines @@
       public aura::WindowObserver,
       public ui::CompositorAnimationObserver {
  public:
   AuraWindowCaptureMachine();
   ~AuraWindowCaptureMachine() override;
 
   // VideoCaptureMachine overrides.
   void Start(const scoped_refptr<media::ThreadSafeCaptureOracle>& oracle_proxy,
              const media::VideoCaptureParams& params,
              const base::Callback<void(bool)> callback) override;
+  void Suspend() override;
+  void Resume() override;
   void Stop(const base::Closure& callback) override;
   void MaybeCaptureForRefresh() override;
 
   // Implements aura::WindowObserver.
   void OnWindowBoundsChanged(aura::Window* window,
                              const gfx::Rect& old_bounds,
                              const gfx::Rect& new_bounds) override;
   void OnWindowDestroying(aura::Window* window) override;
   void OnWindowAddedToRootWindow(aura::Window* window) override;
   void OnWindowRemovingFromRootWindow(aura::Window* window,
                                       aura::Window* new_root) override;
 
   // ui::CompositorAnimationObserver implementation.
   void OnAnimationStep(base::TimeTicks timestamp) override;
   void OnCompositingShuttingDown(ui::Compositor* compositor) override;
 
   // Sets the window to use for capture.
   void SetWindow(aura::Window* window);
 
  private:
   bool InternalStart(
       const scoped_refptr<media::ThreadSafeCaptureOracle>& oracle_proxy,
       const media::VideoCaptureParams& params);
+  void InternalSuspend();
+  void InternalResume();
   void InternalStop(const base::Closure& callback);
 
   // Captures a frame. |event_time| is provided by the compositor, or is null
   // for refresh requests.
   void Capture(base::TimeTicks event_time);
 
   // Update capture size. Must be called on the UI thread.
   void UpdateCaptureSize();
 
   using CaptureFrameCallback =
@@ skipping 40 matching lines @@
   std::unique_ptr<display_compositor::ReadbackYUVInterface>
       yuv_readback_pipeline_;
 
   // Renders mouse cursor on frame.
   std::unique_ptr<content::CursorRendererAura> cursor_renderer_;
 
   // TODO(jiayl): Remove power_save_blocker_ when there is an API to keep the
   // screen from sleeping for the drive-by web.
   std::unique_ptr<device::PowerSaveBlocker> power_save_blocker_;
 
+  // False while frame capture has been suspended. All other aspects of the
+  // machine are maintained.
+  bool frame_capture_active_;
+
   // WeakPtrs are used for the asynchronous capture callbacks passed to external
   // modules.  They are only valid on the UI thread and become invalidated
   // immediately when InternalStop() is called to ensure that no more captured
   // frames will be delivered to the client.
   base::WeakPtrFactory<AuraWindowCaptureMachine> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AuraWindowCaptureMachine);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEDIA_CAPTURE_AURA_WINDOW_CAPTURE_MACHINE_H_