Autoplay: use an autoplay policy setting in Blink.

third_party/WebKit/Source/core/frame/Settings.json5

Index: third_party/WebKit/Source/core/frame/Settings.json5
diff --git a/third_party/WebKit/Source/core/frame/Settings.json5 b/third_party/WebKit/Source/core/frame/Settings.json5
index d9b7c509b3fd1c7bd141b304bc59a0d6feb98d7c..2f4bca9ad9031cec1f68af6b0146520c914a54b4 100644
--- a/third_party/WebKit/Source/core/frame/Settings.json5
+++ b/third_party/WebKit/Source/core/frame/Settings.json5
@@ -216,20 +216,10 @@
     },
 
     {
-      name: "mediaPlaybackRequiresUserGesture",
-      initial: false,
-    },
-    {
       name: "mediaPlaybackGestureWhitelistScope",
       type: "String",
     },
 
-    // This flags overrides mediaPlaybackRequiresUserGesture
-    {
-      name: "crossOriginMediaPlaybackRequiresUserGesture",
-      initial: false,
-    },
-
     {
       name: "presentationRequiresUserGesture",
       initial: true,
@@ -932,5 +922,11 @@
       name: "doNotUpdateSelectionOnMutatingSelectionRange",
       initial: false,
     },
+
+    // Defines the autoplay policy to use.
+    {
+      name: "autoplayPolicy",
+      type: "AutoplayPolicy::Type",
+    },
   ],
 }