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

media/base/clock.cc

Index: media/base/clock.cc
diff --git a/media/base/clock.cc b/media/base/clock.cc
index 2517d1d9c4a9d19115db4ffe423c67247a6e35cb..e57d280658744553c5606481a77274a8b8635a29 100644
--- a/media/base/clock.cc
+++ b/media/base/clock.cc
@@ -72,8 +72,9 @@ void Clock::SetMaxTime(base::TimeDelta max_time) {
   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) {