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

media/capture/content/smooth_event_sampler.h

Index: media/capture/content/smooth_event_sampler.h
diff --git a/media/capture/content/smooth_event_sampler.h b/media/capture/content/smooth_event_sampler.h
index 748ad158de8b319dad332ac7774541ba7e0c9e88..6b69a10cc698eed1525960ba8606f03622a8ef5d 100644
--- a/media/capture/content/smooth_event_sampler.h
+++ b/media/capture/content/smooth_event_sampler.h
@@ -14,7 +14,15 @@
 // Filters a sequence of events to achieve a target frequency.
 class MEDIA_EXPORT SmoothEventSampler {
  public:
-  explicit SmoothEventSampler(base::TimeDelta min_capture_period);
+  enum {
+    // The maximum amount of time that can elapse before considering unchanged
+    // content as dirty for the purposes of timer-based overdue sampling.  This
+    // is the same value found in cc::FrameRateCounter.
+    OVERDUE_DIRTY_THRESHOLD_MILLIS = 250  // 4 FPS
+  };
+
+  SmoothEventSampler(base::TimeDelta min_capture_period,
+                     int redundant_capture_goal);
 
   // Get/Set minimum capture period. When setting a new value, the state of the
   // sampler is retained so that sampling will continue smoothly.
@@ -34,16 +42,22 @@
   // we have sampled the most recent event.
   void RecordSample();
 
+  // Returns true if, at time |event_time|, sampling should occur because too
+  // much time will have passed relative to the last event and/or sample.
+  bool IsOverdueForSamplingAt(base::TimeTicks event_time) const;
+
   // Returns true if ConsiderPresentationEvent() has been called since the last
   // call to RecordSample().
   bool HasUnrecordedEvent() const;
 
  private:
   base::TimeDelta min_capture_period_;
+  const int redundant_capture_goal_;
   base::TimeDelta token_bucket_capacity_;
 
   base::TimeTicks current_event_;
   base::TimeTicks last_sample_;
+  int overdue_sample_count_;
   base::TimeDelta token_bucket_;
 
   DISALLOW_COPY_AND_ASSIGN(SmoothEventSampler);