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

media/base/wall_clock_time_source.cc

Index: media/base/wall_clock_time_source.cc
diff --git a/media/base/wall_clock_time_source.cc b/media/base/wall_clock_time_source.cc
index 036930671babe5bcac3cafc19f137c543c84ac94..bb5074936e82855b1433d82529aa4791912102cf 100644
--- a/media/base/wall_clock_time_source.cc
+++ b/media/base/wall_clock_time_source.cc
@@ -60,15 +60,27 @@ base::TimeDelta WallClockTimeSource::CurrentMediaTime() {
   return CurrentMediaTime_Locked();
 }
 
-base::TimeTicks WallClockTimeSource::GetWallClockTime(base::TimeDelta time) {
-  base::AutoLock auto_lock(lock_);
-  if (!ticking_ || playback_rate_ == 0.0)
+base::TimeTicks WallClockTimeSource::GetWallClockTime(base::TimeDelta time,
+                                                      int request_flags) {
+  if (request_flags & SUSPEND_TIME)
+    lock_.Acquire();
+
+  lock_.AssertAcquired();
+  if (!ticking_ || playback_rate_ == 0.0) {
+    lock_.Release();
     return base::TimeTicks();
+  }
 
   // See notes about |time| values less than |base_time_| in TimeSource header.
-  return reference_wall_ticks_ +
-         base::TimeDelta::FromMicroseconds(
-             (time - base_time_).InMicroseconds() / playback_rate_);
+  const base::TimeTicks result =
+      reference_wall_ticks_ +
+      base::TimeDelta::FromMicroseconds((time - base_time_).InMicroseconds() /
+                                        playback_rate_);
+
+  if (request_flags & RESUME_TIME)
+    lock_.Release();
+
+  return result;
 }
 
 void WallClockTimeSource::SetTickClockForTesting(