Move ContentVideoCaptureDeviceCore from src/content to src/media

content/browser/media/capture/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 CONTENT_BROWSER_MEDIA_CAPTURE_VIDEO_CAPTURE_ORACLE_H_
-#define CONTENT_BROWSER_MEDIA_CAPTURE_VIDEO_CAPTURE_ORACLE_H_
-
-#include "base/callback_forward.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/time/time.h"
-#include "content/browser/media/capture/animated_content_sampler.h"
-#include "content/browser/media/capture/smooth_event_sampler.h"
-#include "content/common/content_export.h"
-#include "ui/gfx/geometry/rect.h"
-
-namespace content {
-
-// 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 CONTENT_EXPORT VideoCaptureOracle {
- public:
-  enum Event {
-    kTimerPoll,
-    kCompositorUpdate,
-    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
-  };
-
-  explicit VideoCaptureOracle(base::TimeDelta min_capture_period);
-  virtual ~VideoCaptureOracle();
-
-  // Record a event of type |event|, and decide whether the caller should do a
-  // frame capture.  |damage_rect| is the region of a frame about to be drawn,
-  // and may be an empty Rect, if this is not known.  If the caller accepts the
-  // oracle's proposal, it should call RecordCapture() to indicate this.
-  bool ObserveEventAndDecideCapture(Event event,
-                                    const gfx::Rect& damage_rect,
-                                    base::TimeTicks event_time);
-
-  // Record the start of a capture.  Returns a frame_number to be used with
-  // CompleteCapture().
-  int RecordCapture();
-
-  // Notify of the completion of a capture, and whether it was successful.
-  // Returns true iff the captured frame should be delivered.  |frame_timestamp|
-  // is set to the timestamp that should be provided to the consumer of the
-  // frame.
-  bool CompleteCapture(int frame_number,
-                       bool capture_was_successful,
-                       base::TimeTicks* frame_timestamp);
-
-  base::TimeDelta min_capture_period() const {
-    return smoothing_sampler_.min_capture_period();
-  }
-
-  // Returns the oracle's estimate of the duration of the next frame.  This
-  // should be called just after ObserveEventAndDecideCapture(), and will only
-  // be non-zero if the call returned true.
-  base::TimeDelta estimated_frame_duration() const {
-    return duration_of_next_frame_;
-  }
-
- private:
-  // Retrieve/Assign a frame timestamp by capture |frame_number|.
-  base::TimeTicks GetFrameTimestamp(int frame_number) const;
-  void SetFrameTimestamp(int frame_number, base::TimeTicks timestamp);
-
-  // Incremented every time a paint or update event occurs.
-  int next_frame_number_;
-
-  // Stores the last |event_time| from the last observation/decision.  Used to
-  // sanity-check that event times are monotonically non-decreasing.
-  base::TimeTicks last_event_time_[kNumEvents];
-
-  // Updated by the last call to ObserveEventAndDecideCapture() with the
-  // estimated duration of the next frame to sample.  This is zero if the method
-  // returned false.
-  base::TimeDelta duration_of_next_frame_;
-
-  // Stores the frame number from the last successfully delivered frame.
-  int last_successfully_delivered_frame_number_;
-
-  // Stores the number of pending frame captures.
-  int num_frames_pending_;
-
-  // These track present/paint history and propose whether to sample each event
-  // for capture.  |smoothing_sampler_| uses a "works for all" heuristic, while
-  // |content_sampler_| specifically detects animated content (e.g., video
-  // playback) and decides which events to sample to "lock into" that content.
-  SmoothEventSampler smoothing_sampler_;
-  AnimatedContentSampler content_sampler_;
-
-  // Recent history of frame timestamps proposed by VideoCaptureOracle.  This is
-  // a ring-buffer, and should only be accessed by the Get/SetFrameTimestamp()
-  // methods.
-  enum { kMaxFrameTimestamps = 16 };
-  base::TimeTicks frame_timestamps_[kMaxFrameTimestamps];
-};
-
-}  // namespace content
-
-#endif  // CONTENT_BROWSER_MEDIA_CAPTURE_VIDEO_CAPTURE_ORACLE_H_