Remove newMediaPlaybackUi flag from content/ and Blink.

third_party/WebKit/LayoutTests/media/video-controls-hidden-audio.html

Index: third_party/WebKit/LayoutTests/media/video-controls-hidden-audio.html
diff --git a/third_party/WebKit/LayoutTests/media/video-controls-hidden-audio.html b/third_party/WebKit/LayoutTests/media/video-controls-hidden-audio.html
index 296918812aff8288cafa0945d2cbd99618dddcc9..dcccca0efbfcdaa180266a5819e63fe3334ffbf1 100644
--- a/third_party/WebKit/LayoutTests/media/video-controls-hidden-audio.html
+++ b/third_party/WebKit/LayoutTests/media/video-controls-hidden-audio.html
@@ -10,8 +10,6 @@ async_test(function(t) {
     var video = document.querySelector("video");
 
     video.oncanplaythrough = t.step_func_done(function() {
-        // Enable hidden audio preferences to take effect.
-        internals.setAllowHiddenVolumeControls(video, true);
         // Request non-hidden audio controls.
         internals.settings.setPreferHiddenVolumeControls(false);
         video.muted = false;
@@ -43,4 +41,4 @@ async_test(function(t) {
 
     video.src = findMediaFile("video", "content/test");
 })
-</script>
+</script>