FakeVideoCaptureDevice: Regulate framerate without drifting

media/video/capture/fake_video_capture_device.h

Index: media/video/capture/fake_video_capture_device.h
diff --git a/media/video/capture/fake_video_capture_device.h b/media/video/capture/fake_video_capture_device.h
index f4a19f9edb9c2c6611aa8d66cc15094f905ead7f..3cf45a85581d9073dd7ef111dcad5f8028f51643 100644
--- a/media/video/capture/fake_video_capture_device.h
+++ b/media/video/capture/fake_video_capture_device.h
@@ -15,6 +15,7 @@
 #include "base/memory/weak_ptr.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_checker.h"
+#include "base/time/time.h"
 #include "media/video/capture/video_capture_device.h"
 
 namespace media {
@@ -41,9 +42,12 @@ class MEDIA_EXPORT FakeVideoCaptureDevice : public VideoCaptureDevice {
  private:
   static const int kFakeCapturePeriodMs = 50;
 
-  void CaptureUsingOwnBuffers();
-  void CaptureUsingClientBuffers(VideoPixelFormat pixel_format);
-  void BeepAndScheduleNextCapture(const base::Closure& next_capture);
+  void CaptureUsingOwnBuffers(base::TimeTicks expected_execution_time);
+  void CaptureUsingClientBuffers(VideoPixelFormat pixel_format,
+                                 base::TimeTicks expected_execution_time);
+  void BeepAndScheduleNextCapture(
+      base::TimeTicks expected_execution_time,
+      const base::Callback<void(base::TimeTicks)>& next_capture);
 
   // |thread_checker_| is used to check that all methods are called in the
   // correct thread that owns the object.