Change Clock::SetMaxTime() to be safe even in the presence of slow pipelines.

media/base/clock.cc

 // Copyright (c) 2012 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/clock.h"
 
 #include "base/logging.h"
 #include "media/base/buffers.h"
 
 namespace media {
@@ skipping 54 matching lines @@
 
   return elapsed;
 }
 
 void Clock::SetMaxTime(base::TimeDelta max_time) {
   DCHECK(max_time != kNoTimestamp());
 
   UpdateReferencePoints();
   max_time_ = ClampToValidTimeRange(max_time);
 
-  DCHECK(media_time_ <= max_time_);
-  underflow_ = false;
+  underflow_ = media_time_ > max_time_;
+  if (underflow_)
+    media_time_ = max_time_;

[vrk (LEFT CHROMIUM), 2012/03/05 22:18:08]

Technically this assignment is incorrect: you want to set |media_time_| to the
current time, not the max time. However, the effect of this is very minor since
max time is only a few frames ahead of the current time, and because of the way
the video renderer works, I believe everything works out fine for every
subsequent call to SetMaxTime().

I filed crbug.com/116856. As I say in the bug, I think it should still be fixed
for code sanity purposes, despite the low-impact.

 }
 
 void Clock::SetDuration(base::TimeDelta duration) {
   DCHECK(duration_ == kNoTimestamp());
   DCHECK(duration > base::TimeDelta());
   duration_ = duration;
 }
 
 base::TimeDelta Clock::ElapsedViaProvidedTime(const base::Time& time) const {
   // TODO(scherkus): floating point badness scaling time by playback rate.
@@ skipping 43 matching lines @@
   playing_ = false;
   playback_rate_ = 1.0f;
   max_time_ = kNoTimestamp();
   duration_ = kNoTimestamp();
   media_time_ = base::TimeDelta();
   reference_ = base::Time();
   underflow_ = false;
 }
 
 }  // namespace media