Move capture scheduling logic from VideoScheduler to CaptureScheduler.

remoting/host/capture_scheduler.h

 // Copyright (c) 2011 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.
 
 // This class chooses a capture interval so as to limit CPU usage to not exceed
 // a specified %age. It bases this on the CPU usage of recent capture and encode
 // operations, and on the number of available CPUs.
 
 #ifndef REMOTING_HOST_CAPTURE_SCHEDULER_H_
 #define REMOTING_HOST_CAPTURE_SCHEDULER_H_
 
+#include "base/callback.h"
+#include "base/threading/non_thread_safe.h"
+#include "base/time/tick_clock.h"
 #include "base/time/time.h"
+#include "base/timer/timer.h"
 #include "remoting/base/running_average.h"
 
 namespace remoting {
 
-class CaptureScheduler {
+// CaptureScheduler is used by the VideoScheduler to scheduler frame capturer,

[Wez, 2015/02/02 21:40:49]

s/scheduler/schedule

[Sergey Ulanov, 2015/02/03 23:49:52]

Done.

+// taking into account capture delay, encoder delay, network bandwidth, etc.
+class CaptureScheduler : public base::NonThreadSafe {
  public:
-  CaptureScheduler();
+  explicit CaptureScheduler(const base::Closure& capture_closure);

[Wez, 2015/02/02 21:40:48]

Suggest adding a comment to explain that |capture_closure| will be called each
time a capture should be performed.

[Sergey Ulanov, 2015/02/03 23:49:52]

Done.

   ~CaptureScheduler();
 
-  // Returns the time to wait after initiating a capture before triggering
-  // the next.
-  base::TimeDelta NextCaptureDelay();
+  // Starts the scheduler.
+  void Start();
 
-  // Records time spent on capturing and encoding.
-  void RecordCaptureTime(base::TimeDelta capture_time);
-  void RecordEncodeTime(base::TimeDelta encode_time);
+  // Pauses or unpauses the stream.
+  void Pause(bool pause);
+
+  // Notifies the scheduler that a capture has been completed.
+  void OnCaptureCompleted();
+
+  // Notifies the scheduler than a frame has been encoded.

[Wez, 2015/02/02 21:40:48]

s/than/that

[Sergey Ulanov, 2015/02/03 23:49:52]

Done.

+  void OnFrameEncoded(base::TimeDelta encode_time);
+
+  // Notifies the scheduler than a frame has been sent.

[Wez, 2015/02/02 21:40:48]

s/than/that

[Sergey Ulanov, 2015/02/03 23:49:52]

Done.

+  void OnFrameSent();
 
   // Sets minimum interval between frames.
   void set_minimum_interval(base::TimeDelta minimum_interval) {
     minimum_interval_ = minimum_interval;
   }
 
-  // Overrides the number of processors for testing.
-  void SetNumOfProcessorsForTest(int num_of_processors);
+  // Helper functions for tests.
+  void set_tick_clock_for_tests(scoped_ptr<base::TickClock> tick_clock) {

[Wez, 2015/02/02 21:40:48]

nit: Should these be SetTickClockForTest and similar?

If not then they should end ..._for_test() rather than _for_tests(), to match
the presubmit rule.

[Sergey Ulanov, 2015/02/03 23:49:52]

Done.

+    tick_clock_ = tick_clock.Pass();
+  }
+  void set_timer_for_tests(scoped_ptr<base::Timer> timer) {
+    capture_timer_ = timer.Pass();
+  }
+  void set_num_of_processors_for_tests(int num_of_processors) {
+    num_of_processors_ = num_of_processors;
+  }
 
  private:
+  // Schedules |capture_timer_| to call CaptureNextFrame() at appropriate time.
+  // Doesn't do anything if next frame cannot be captured yet (e.g. because
+  // there are too many frames being processed).
+  void ScheduleNextCapture();
+
+  // Called by |capture_timer_|. Calls |capture_closure_| to start capturing a
+  // new frame.
+  void CaptureNextFrame();
+
+  base::Closure capture_closure_;
+
+  scoped_ptr<base::TickClock> tick_clock_;
+
+  // Timer used to schedule CaptureNextFrame().
+  scoped_ptr<base::Timer> capture_timer_;
+
+  // Minimum interval between frames.

[Wez, 2015/02/02 21:40:48]

How is this set and what's it used for?

[Sergey Ulanov, 2015/02/03 23:49:52]

Removed it.

   base::TimeDelta minimum_interval_;
+
   int num_of_processors_;
+
   RunningAverage capture_time_;
   RunningAverage encode_time_;
 
+  int pending_frames_;

[Wez, 2015/02/02 21:40:48]

What does it mean for a frame to be "pending" - from the code it seems that a
frame is pending from the moment it is scheduled for capture to the moment it is
sent to the wire?

Can you add comments to explain how this block of members are used, e.g. what is
|last_capture_started_time| used for?

[Sergey Ulanov, 2015/02/03 23:49:52]

Done.

+  bool capture_pending_;
+  base::TimeTicks last_capture_started_time_;
+  bool is_paused_;
+
   DISALLOW_COPY_AND_ASSIGN(CaptureScheduler);
 };
 
 }  // namespace remoting
 
 #endif  // REMOTING_HOST_CAPTURE_SCHEDULER_H_