Improve HTMLMediaElement::currentTime()

third_party/WebKit/Source/modules/mediasource/SourceBuffer.cpp

Index: third_party/WebKit/Source/modules/mediasource/SourceBuffer.cpp
diff --git a/third_party/WebKit/Source/modules/mediasource/SourceBuffer.cpp b/third_party/WebKit/Source/modules/mediasource/SourceBuffer.cpp
index edd871b1675cf603fd6a88dcff96d588e3124db2..8c7a5b106b59df8917ca7a005545a44598095731 100644
--- a/third_party/WebKit/Source/modules/mediasource/SourceBuffer.cpp
+++ b/third_party/WebKit/Source/modules/mediasource/SourceBuffer.cpp
@@ -1157,6 +1157,13 @@ bool SourceBuffer::prepareAppend(size_t newDataSize,
 bool SourceBuffer::evictCodedFrames(size_t newDataSize) {
   DCHECK(m_source);
   DCHECK(m_source->mediaElement());
+
+  // Nothing to do if the mediaElement does not yet have frames to evict.
+  // mediaElement()->currentTime() will be NaN.
+  if (m_source->mediaElement()->getReadyState() <
+      HTMLMediaElement::kHaveMetadata)
+    return true;

[mlamouri (slow - plz ping), 2016/10/26 15:32:54]

style: wrap in { }

Would it make sense to check for currentTime(0 ==
std::numeric_limits<double>quiet_NaN() instead of the ready state?

[chcunningham, 2016/10/26 19:29:41]

Done.
This NaN issue actually disappeared once I realized NaN was not the right value
to initialize official/current position to (now using 0). 

I still think this is a nice optimization, so I'll leave it. Checking readyState
is the right thing, since currentTime can be zero irrespective of whether we
have data to consider evicting.

+
   double currentTime = m_source->mediaElement()->currentTime();
   bool result = m_webSourceBuffer->evictCodedFrames(currentTime, newDataSize);
   if (!result) {