Create autoplay policy flag and merge cross-origin autoplay blocking into it.

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 311 matching lines @@
 // https://w3c.github.io/web-nfc/
 const base::Feature kWebNfc{"WebNFC", base::FEATURE_DISABLED_BY_DEFAULT};
 #endif
 
 #if !defined(OS_ANDROID)
 // The JavaScript API for payments on the web.
 const base::Feature kWebPayments{"WebPayments",
                                  base::FEATURE_DISABLED_BY_DEFAULT};
 #endif
 
-#if !defined(OS_ANDROID)
-// Controls whether media playback in cross-origin iframes is enabled. The
-// feature overrides |kDisableGestureRequirementForMediaPlayback|.
-const base::Feature kCrossOriginMediaPlaybackRequiresUserGesture{
-    "CrossOriginMediaPlaybackRequiresUserGesture",
-    base::FEATURE_DISABLED_BY_DEFAULT};
-#endif  // !defined(OS_ANDROID)
-
 #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