Mark HTMLMediaElement media tracks functionality as stable

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 14fb000eb3b4d0f6b848663431438202fb9d19ff..09322311bbf39c63fa92af8ae6b1a60d5728c797 100644
--- a/third_party/WebKit/Source/modules/mediasource/SourceBuffer.cpp
+++ b/third_party/WebKit/Source/modules/mediasource/SourceBuffer.cpp
@@ -243,13 +243,11 @@ void SourceBuffer::setTimestampOffset(double offset, ExceptionState& exceptionSt
 
 AudioTrackList& SourceBuffer::audioTracks()
 {
-    DCHECK(RuntimeEnabledFeatures::audioVideoTracksEnabled());
     return *m_audioTracks;
 }
 
 VideoTrackList& SourceBuffer::videoTracks()
 {
-    DCHECK(RuntimeEnabledFeatures::audioVideoTracksEnabled());
     return *m_videoTracks;
 }
 
@@ -522,12 +520,10 @@ void SourceBuffer::removedFromMediaSource()
         abortIfUpdating();
     }
 
-    if (RuntimeEnabledFeatures::audioVideoTracksEnabled()) {
-        DCHECK(m_source);
-        if (m_source->mediaElement()->audioTracks().length() > 0
-            || m_source->mediaElement()->videoTracks().length() > 0) {
-            removeMediaTracks();
-        }
+    DCHECK(m_source);
+    if (m_source->mediaElement()->audioTracks().length() > 0
+        || m_source->mediaElement()->videoTracks().length() > 0) {
+        removeMediaTracks();
     }
 
     m_webSourceBuffer->removedFromMediaSource();
@@ -547,7 +543,6 @@ double SourceBuffer::highestPresentationTimestamp()
 
 void SourceBuffer::removeMediaTracks()
 {
-    DCHECK(RuntimeEnabledFeatures::audioVideoTracksEnabled());
     // Spec: http://w3c.github.io/media-source/#widl-MediaSource-removeSourceBuffer-void-SourceBuffer-sourceBuffer
     DCHECK(m_source);
 
@@ -667,14 +662,6 @@ bool SourceBuffer::initializationSegmentReceived(const WebVector<MediaTrackInfo>
     DCHECK(m_source->mediaElement());
     DCHECK(m_updating);
 
-    if (!RuntimeEnabledFeatures::audioVideoTracksEnabled()) {
-        if (!m_firstInitializationSegmentReceived) {
-            m_source->setSourceBufferActive(this);
-            m_firstInitializationSegmentReceived = true;
-        }
-        return true;
-    }
-
     // Implementation of Initialization Segment Received, see
     // https://w3c.github.io/media-source/#sourcebuffer-init-segment-received