Tab/Desktop Capture: Use requests instead of timer-based refreshing.

media/capture/content/video_capture_oracle.h

 // 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.
 
 #ifndef MEDIA_CAPTURE_CONTENT_VIDEO_CAPTURE_ORACLE_H_
 #define MEDIA_CAPTURE_CONTENT_VIDEO_CAPTURE_ORACLE_H_
 
 #include "base/callback_forward.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 #include "media/base/media_export.h"
 #include "media/capture/content/animated_content_sampler.h"
 #include "media/capture/content/capture_resolution_chooser.h"
 #include "media/capture/content/feedback_signal_accumulator.cc"
 #include "media/capture/content/smooth_event_sampler.h"
 #include "ui/gfx/geometry/rect.h"
 
 namespace media {
 
 // VideoCaptureOracle manages the producer-side throttling of captured frames
 // from a video capture device.  It is informed of every update by the device;
 // this empowers it to look into the future and decide if a particular frame
 // ought to be captured in order to achieve its target frame rate.
 class MEDIA_EXPORT VideoCaptureOracle {
  public:
   enum Event {
-    kTimerPoll,
     kCompositorUpdate,
+    kActiveRefreshRequest,
+    kPassiveRefreshRequest,
     kMouseCursorUpdate,
     kNumEvents,
   };
 
-  enum {
-    // The recommended minimum amount of time between calls to
-    // ObserveEventAndDecideCapture() for the kTimerPoll Event type.  Anything
-    // lower than this isn't harmful, just wasteful.
-    kMinTimerPollPeriodMillis = 125,  // 8 FPS
-  };
-
   VideoCaptureOracle(base::TimeDelta min_capture_period,
                      const gfx::Size& max_frame_size,
                      media::ResolutionChangePolicy resolution_change_policy,
                      bool enable_auto_throttling);
 
   virtual ~VideoCaptureOracle();
 
   // Sets the source content size.  This may not have an immediate effect on the
   // proposed capture size, as the oracle will prevent too-frequent changes from
   // occurring.
@@ skipping 47 matching lines @@
   // Returns the capture frame size the client should use.  This is updated by
   // calls to ObserveEventAndDecideCapture().  The oracle prevents too-frequent
   // changes to the capture size, to avoid stressing the end-to-end pipeline.
   gfx::Size capture_size() const { return capture_size_; }
 
   // Returns the oracle's estimate of the last time animation was detected.
   base::TimeTicks last_time_animation_was_detected() const {
     return last_time_animation_was_detected_;
   }
 
+  // Returns a NUL-terminated string containing a short, human-readable form of
+  // |event|.
+  static const char* EventAsString(Event event);
+
  private:
   // Retrieve/Assign a frame timestamp by capture |frame_number|.  Only valid
   // when IsFrameInRecentHistory(frame_number) returns true.
   base::TimeTicks GetFrameTimestamp(int frame_number) const;
   void SetFrameTimestamp(int frame_number, base::TimeTicks timestamp);
 
   // Returns true if the frame timestamp ring-buffer currently includes a
   // slot for the given |frame_number|.
   bool IsFrameInRecentHistory(int frame_number) const;
 
@@ skipping 82 matching lines @@
 
   // The timestamp of the frame where |content_sampler_| last detected
   // animation.  This determines whether capture size increases will be
   // aggressive (because content is not animating).
   base::TimeTicks last_time_animation_was_detected_;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_CAPTURE_CONTENT_VIDEO_CAPTURE_ORACLE_H_