Allow callers of TimeSource::GetWallClockTime() to suspend time.

media/filters/video_renderer_algorithm.cc

Index: media/filters/video_renderer_algorithm.cc
diff --git a/media/filters/video_renderer_algorithm.cc b/media/filters/video_renderer_algorithm.cc
index 5bad074339eb2f420bd39a3652079f63738cfa41..b1817d457480ef25e04843a334d436369f0ef812 100644
--- a/media/filters/video_renderer_algorithm.cc
+++ b/media/filters/video_renderer_algorithm.cc
@@ -30,13 +30,13 @@ bool VideoRendererAlgorithm::ReadyFrame::operator<(
 }
 
 VideoRendererAlgorithm::VideoRendererAlgorithm(
-    const TimeConverterCB& time_converter_cb)
+    const TimeSource::WallClockTimeCB& wall_clock_time_cb)
     : cadence_estimator_(base::TimeDelta::FromSeconds(
           kMinimumAcceptableTimeBetweenGlitchesSecs)),
-      time_converter_cb_(time_converter_cb),
+      wall_clock_time_cb_(wall_clock_time_cb),
       frame_duration_calculator_(kMovingAverageSamples),
       frame_dropping_disabled_(false) {
-  DCHECK(!time_converter_cb_.is_null());
+  DCHECK(!wall_clock_time_cb_.is_null());
   Reset();
 }
 
@@ -381,7 +381,14 @@ bool VideoRendererAlgorithm::UpdateFrameStatistics() {
   for (size_t i = 0; i < frame_queue_.size(); ++i) {
     ReadyFrame& frame = frame_queue_[i];
     const bool new_frame = frame.start_time.is_null();
-    frame.start_time = time_converter_cb_.Run(frame.frame->timestamp());
+    frame.start_time = wall_clock_time_cb_.Run(
+        frame.frame->timestamp(),
+        frame_queue_.size() == 1
+            ? TimeSource::SINGLE_TIMESTAMP
+            : (i == 0 ? TimeSource::SUSPEND_TIME
+                      : (i + 1 == frame_queue_.size()
+                             ? TimeSource::RESUME_TIME
+                             : TimeSource::TIME_IS_SUSPENDED)));
 
     // If time stops or never started, exit immediately.
     if (frame.start_time.is_null()) {
@@ -389,16 +396,14 @@ bool VideoRendererAlgorithm::UpdateFrameStatistics() {
       return false;
     }
 
-    // TODO(dalecurtis): An unlucky tick of a playback rate change could cause
-    // this to skew so much that time goes backwards between calls.  Fix this by
-    // either converting all timestamps at once or with some retry logic.
     if (i > 0) {
       frame_queue_[i - 1].end_time = frame.start_time;
-      const base::TimeDelta delta =
-          frame.start_time - frame_queue_[i - 1].start_time;
-      CHECK_GT(delta, base::TimeDelta());
-      if (new_frame)
+      if (new_frame) {
+        const base::TimeDelta delta =
+            frame.start_time - frame_queue_[i - 1].start_time;
+        DCHECK_GT(delta, base::TimeDelta());
         frame_duration_calculator_.AddSample(delta);
+      }
     }
   }