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

chrome/browser/flag_descriptions.cc

 // Copyright 2017 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 "chrome/browser/flag_descriptions.h"
 
 namespace flag_descriptions {
 
 //  Material Design version of chrome://bookmarks
 
@@ skipping 636 matching lines @@
 
 const char kEnableTokenBindingDescription[] = "Enable Token Binding support.";
 
 const char kGestureRequirementForMediaPlaybackName[] =
     "Gesture requirement for media playback";
 
 const char kGestureRequirementForMediaPlaybackDescription[] =
     "User gesture requirement for playing media elements. Disabling this "
     "will allow autoplay to work.";
 
-#if !defined(OS_ANDROID)
-
-const char kCrossOriginMediaPlaybackRequiresUserGestureName[] =
-    "Media playback in cross-origin iframes requires user gesture";
-
-const char kCrossOriginMediaPlaybackRequiresUserGestureDescription[] =
-    "Playing media elements in cross-origin iframes requires user gesture. "
-    "Disabling this will allow autoplay in cross-origin iframes to work.";
-
-#endif  // !defined(OS_ANDROID)
-
 const char kPassiveDocumentEventListenersDescription[] =
     "Forces touchstart, and touchmove event listeners on document level "
     "targets (which haven't requested otherwise) to be treated as passive.";
 
 const char kPassiveDocumentEventListenersName[] =
     "Document Level Event Listeners Passive Default";
 
 const char kPassiveEventListenersDueToFlingDescription[] =
     "Forces touchstart, and first touchmove per scroll event listeners "
     "during fling to be treated as passive.";
@@ skipping 2362 matching lines @@
 
 const char kEnableOmniboxClipboardProviderName[] =
     "Omnibox clipboard URL suggestions";
 
 const char kEnableOmniboxClipboardProviderDescription[] =
     "Provide a suggestion of the URL stored in the clipboard (if any) upon "
     "focus in the omnibox.";
 
 #endif  // defined(OS_ANDROID)
 
+const char kAutoplayPolicyName[] = "Autoplay policy";
+
+const char kAutoplayPolicyDescription[] =
+    "Policy used when deciding if audio or video is allowed to autoplay.";
+
+const char kAutoplayPolicyNoUserGestureRequired[] =
+    "No user gesture is required.";
+
+const char kAutoplayPolicyUserGestureRequired[] = "User gesture is required.";
+
+const char kAutoplayPolicyCrossOriginUserGestureRequired[] =
+    "User gesture is required for cross-origin iframes.";
+
 }  // namespace flag_descriptions