Remove newMediaPlaybackUi flag from content/ and Blink.

content/child/runtime_features.cc

Index: content/child/runtime_features.cc
diff --git a/content/child/runtime_features.cc b/content/child/runtime_features.cc
index 15e6f8e8b7807d322a1e4404332430fd6eb664aa..1cf707331344d6d379e07ed5bb288c204df23b0b 100644
--- a/content/child/runtime_features.cc
+++ b/content/child/runtime_features.cc
@@ -39,7 +39,6 @@ static void SetRuntimeFeatureDefaultsForPlatform() {
   // Android won't be able to reliably support non-persistent notifications, the
   // intended behavior for which is in flux by itself.
   WebRuntimeFeatures::enableNotificationConstructor(false);
-  WebRuntimeFeatures::enableNewMediaPlaybackUi(true);
   // Android does not yet support switching of audio output devices
   WebRuntimeFeatures::enableAudioOutputDevices(false);
 #else
@@ -241,11 +240,6 @@ void SetRuntimeFeaturesDefaultsAndUpdateFromArgs(
   if (command_line.HasSwitch(switches::kEnableSlimmingPaintV2))
     WebRuntimeFeatures::enableSlimmingPaintV2(true);
 
-  // Note that it might already by true for OS_ANDROID, above.  This is for
-  // non-android versions.
-  if (base::FeatureList::IsEnabled(features::kNewMediaPlaybackUi))
-    WebRuntimeFeatures::enableNewMediaPlaybackUi(true);
-
   if (base::FeatureList::IsEnabled(
           features::kNonValidatingReloadOnNormalReload)) {
     WebRuntimeFeatures::enableReloadwithoutSubResourceCacheRevalidation(true);