Remove newMediaPlaybackUi flag from content/ and Blink.

content/public/common/content_features.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "build/build_config.h"
 #include "content/public/common/content_features.h"
 
 namespace features {
 
 // All features in alphabetical order.
@@ skipping 74 matching lines @@
 };
 
 // Enables the memory coordinator.
 // WARNING:
 // The memory coordinator is not ready for use and enabling this may cause
 // unexpected memory regression at this point. Please do not enable this.
 const base::Feature kMemoryCoordinator {
   "MemoryCoordinator", base::FEATURE_DISABLED_BY_DEFAULT
 };
 
-// Enable the material design playback UI for media elements.  This is always
-// on for OS_ANDROID, but may be enabled by experiment for other platforms.
-const base::Feature kNewMediaPlaybackUi{"NewMediaPlaybackUi",
-                                        base::FEATURE_ENABLED_BY_DEFAULT};
-
 // Non-validating reload for desktop.
 // See https://crbug.com/591245
 const base::Feature kNonValidatingReloadOnNormalReload{
     "NonValidatingReloadOnNormalReload", base::FEATURE_ENABLED_BY_DEFAULT};
 
 // Non-validating reload on reload-to-refresh-content (e.g. pull-to-refresh).
 // See https://crbug.com/591245
 const base::Feature kNonValidatingReloadOnRefreshContent{
     "NonValidatingReloadOnRefreshContentV2",
     base::FEATURE_ENABLED_BY_DEFAULT};
@@ skipping 130 matching lines @@
 #endif
 
 #if defined(OS_WIN)
 // Emergency "off switch" for new Windows sandbox security mitigation,
 // sandbox::MITIGATION_EXTENSION_POINT_DISABLE.
 const base::Feature kWinSboxDisableExtensionPoints{
     "WinSboxDisableExtensionPoint", base::FEATURE_ENABLED_BY_DEFAULT};
 #endif
 
 }  // namespace features