Bug 992685 - Part 2. Fire resize event when video size changes. r=roc

dom/html/HTMLMediaElement.cpp

@@ -3002,6 +3002,10 @@ void HTMLMediaElement::MetadataLoaded(const MediaInfo* aInfo,
   mLoadedDataFired = false;
   ChangeReadyState(nsIDOMHTMLMediaElement::HAVE_METADATA);
   DispatchAsyncEvent(NS_LITERAL_STRING("durationchange"));
+  if (IsVideo() && mHasVideo) {
+    mMediaSize = aInfo->mVideo.mDisplay;
+    DispatchAsyncEvent(NS_LITERAL_STRING("resize"));
+  }
   DispatchAsyncEvent(NS_LITERAL_STRING("loadedmetadata"));
   if (mDecoder && mDecoder->IsTransportSeekable() && mDecoder->IsMediaSeekable()) {
     ProcessMediaFragmentURI();
@@ -3642,6 +3646,10 @@ void HTMLMediaElement::NotifyDecoderPrincipalChanged()
 
 void HTMLMediaElement::UpdateMediaSize(nsIntSize size)
 {
+  if (IsVideo() && mReadyState != HAVE_NOTHING && mMediaSize != size) {
+    DispatchAsyncEvent(NS_LITERAL_STRING("resize"));
+  }
+
   mMediaSize = size;
   UpdateReadyStateForData(mLastNextFrameStatus);
 }