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

media/capture/content/smooth_event_sampler.cc

Index: media/capture/content/smooth_event_sampler.cc
diff --git a/media/capture/content/smooth_event_sampler.cc b/media/capture/content/smooth_event_sampler.cc
index 7f7297f2038192655b24528e4ae29db1778d1c53..9ac263dd13fc2a8c91c30fb8a3dc22e2de1fb858 100644
--- a/media/capture/content/smooth_event_sampler.cc
+++ b/media/capture/content/smooth_event_sampler.cc
@@ -12,8 +12,11 @@
 
 namespace media {
 
-SmoothEventSampler::SmoothEventSampler(base::TimeDelta min_capture_period)
-    : token_bucket_(base::TimeDelta::Max()) {
+SmoothEventSampler::SmoothEventSampler(base::TimeDelta min_capture_period,
+                                       int redundant_capture_goal)
+    : redundant_capture_goal_(redundant_capture_goal),
+      overdue_sample_count_(0),
+      token_bucket_(base::TimeDelta::Max()) {
   SetMinCapturePeriod(min_capture_period);
 }
 
@@ -56,8 +59,29 @@
   TRACE_COUNTER1("gpu.capture", "MirroringTokenBucketUsec",
                  std::max<int64_t>(0, token_bucket_.InMicroseconds()));
 
-  if (HasUnrecordedEvent())
+  if (HasUnrecordedEvent()) {
     last_sample_ = current_event_;
+    overdue_sample_count_ = 0;
+  } else {
+    ++overdue_sample_count_;
+  }
+}
+
+bool SmoothEventSampler::IsOverdueForSamplingAt(
+    base::TimeTicks event_time) const {
+  DCHECK(!event_time.is_null());
+
+  if (!HasUnrecordedEvent() && overdue_sample_count_ >= redundant_capture_goal_)
+    return false;  // Not dirty.
+
+  if (last_sample_.is_null())
+    return true;
+
+  // If we're dirty but not yet old, then we've recently gotten updates, so we
+  // won't request a sample just yet.
+  base::TimeDelta dirty_interval = event_time - last_sample_;
+  return dirty_interval >=
+         base::TimeDelta::FromMilliseconds(OVERDUE_DIRTY_THRESHOLD_MILLIS);
 }
 
 bool SmoothEventSampler::HasUnrecordedEvent() const {