bug 1194558 correct time conversion for video frame timestamps r=roc

MediaTimeToSeconds() works fine for negative intervals

--HG--
extra : rebase_source : 8698761e28a54e6bd172a032c62e03b96ac66bfa

dom/media/MediaStreamGraph.cpp

@@ -1166,7 +1166,7 @@ MediaStreamGraphImpl::PlayVideo(MediaStream* aStream)
   GraphTime startTime = StreamTimeToGraphTime(aStream,
       start, INCLUDE_TRAILING_BLOCKED_INTERVAL);
   TimeStamp targetTime = CurrentDriver()->GetCurrentTimeStamp() +
-      TimeDuration::FromMilliseconds(double(startTime - IterationEnd()));
+      TimeDuration::FromSeconds(MediaTimeToSeconds(startTime - IterationEnd()));
   for (uint32_t i = 0; i < aStream->mVideoOutputs.Length(); ++i) {
     VideoFrameContainer* output = aStream->mVideoOutputs[i];
 

dom/media/MediaStreamGraphImpl.h

@@ -448,7 +448,8 @@ public:
 
   double MediaTimeToSeconds(GraphTime aTime) const
   {
-    NS_ASSERTION(0 <= aTime && aTime <= STREAM_TIME_MAX, "Bad time");
+    NS_ASSERTION(aTime > -STREAM_TIME_MAX && aTime <= STREAM_TIME_MAX,
+                 "Bad time");
     return static_cast<double>(aTime)/GraphRate();
   }