Enable smooth transition when show/hide media remoting interstitial.

third_party/WebKit/Source/core/html/HTMLVideoElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLVideoElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLVideoElement.cpp b/third_party/WebKit/Source/core/html/HTMLVideoElement.cpp
index c8fa9d8076710e439c8767005e9b61272a3308c3..c5d0e39ed1d7b23c82ff5eda135b93917736935a 100644
--- a/third_party/WebKit/Source/core/html/HTMLVideoElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLVideoElement.cpp
@@ -504,9 +504,13 @@ void HTMLVideoElement::MediaRemotingStarted() {
 }
 
 void HTMLVideoElement::MediaRemotingStopped() {
-  if (media_remoting_status_ != MediaRemotingStatus::kDisabled)
-    media_remoting_status_ = MediaRemotingStatus::kNotStarted;
+  // Early return because this was already called when media remoting was
+  // disabled.
+  if (media_remoting_status_ == MediaRemotingStatus::kDisabled)
+    return;
+  DCHECK_EQ(media_remoting_status_, MediaRemotingStatus::kStarted);

[mlamouri (slow - plz ping), 2017/04/19 17:58:46]

nit: swap the two parameters -- Also, I can't remember if MediaRemotingStatus is
an enum class but if that's the case, some compilers might not accept this and
you will have to do DCHECK(foo == bar)

[xjz, 2017/04/19 18:08:10]

Done. Yes, MediaRemotingStatus is an enum class. Changed to DCHECK(foo == bar)
now.

   DCHECK(remoting_interstitial_);
+  media_remoting_status_ = MediaRemotingStatus::kNotStarted;
   remoting_interstitial_->Hide();
 }