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

media/base/wall_clock_time_source.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/base/wall_clock_time_source.h"
 
 #include "base/logging.h"
 #include "base/time/default_tick_clock.h"
 
 namespace media {
@@ skipping 42 matching lines @@
   base::AutoLock auto_lock(lock_);
   CHECK(!ticking_);
   base_time_ = time;
 }
 
 base::TimeDelta WallClockTimeSource::CurrentMediaTime() {
   base::AutoLock auto_lock(lock_);
   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(
     scoped_ptr<base::TickClock> tick_clock) {
   tick_clock_.swap(tick_clock);
 }
 
 base::TimeDelta WallClockTimeSource::CurrentMediaTime_Locked() {
   lock_.AssertAcquired();
   if (!ticking_ || playback_rate_ == 0.0)
     return base_time_;
 
   base::TimeTicks now = tick_clock_->NowTicks();
   return base_time_ +
          base::TimeDelta::FromMicroseconds(
              (now - reference_wall_ticks_).InMicroseconds() * playback_rate_);
 }
 
 }  // namespace media