Autoplay: use an autoplay policy setting in Blink.

third_party/WebKit/public/web/WebSettings.h

Index: third_party/WebKit/public/web/WebSettings.h
diff --git a/third_party/WebKit/public/web/WebSettings.h b/third_party/WebKit/public/web/WebSettings.h
index e9f91d6b314343dc0da7c3b2156df45dfbd47966..b2ae0b050eddc28545b094a8346bdf0d57a12720 100644
--- a/third_party/WebKit/public/web/WebSettings.h
+++ b/third_party/WebKit/public/web/WebSettings.h
@@ -113,6 +113,14 @@ class WebSettings {
     kForceAllTrue  // Force all values to be true even when specified.
   };
 
+  // Defines the autoplay policy to be used. Should match the enum class in
+  // web_preferences.h

[dcheng, 2017/04/27 15:57:17]

Is this in another CL? Or is this referencing AutoplayPolicy::Type?

+  enum class AutoplayPolicy {
+    kNoUserGestureRequired = 0,
+    kCrossOriginUserGestureRequired,

[dcheng, 2017/04/27 15:57:17]

FWIW, I find this name a bit confusing: to me, it reads "cross-origin user
gesture", where cross-origin is modifying user gesture, rather than "autoplay in
cross-origin subframe requires user gesture". *shrug*

kUserGestureRequiredForCrossOriginSubframe might be clearer, though it's also
more verbose.

+    kUserGestureRequired,
+  };
+
   // Sets value of a setting by its string identifier from Settings.in and
   // string representation of value. An enum's string representation is the
   // string representation of the integer value of the enum.
@@ -145,11 +153,11 @@ class WebSettings {
   virtual void SetAlwaysShowContextMenuOnTouch(bool) = 0;
   virtual void SetAntialiased2dCanvasEnabled(bool) = 0;
   virtual void SetAntialiasedClips2dCanvasEnabled(bool) = 0;
+  virtual void SetAutoplayPolicy(AutoplayPolicy) = 0;
   virtual void SetAutoZoomFocusedNodeToLegibleScale(bool) = 0;
   virtual void SetBrowserSideNavigationEnabled(bool) = 0;
   virtual void SetClobberUserAgentInitialScaleQuirk(bool) = 0;
   virtual void SetCookieEnabled(bool) = 0;
-  virtual void SetCrossOriginMediaPlaybackRequiresUserGesture(bool) = 0;
   virtual void SetNavigateOnDragDrop(bool) = 0;
   virtual void SetCursiveFontFamily(const WebString&,
                                     UScriptCode = USCRIPT_COMMON) = 0;
@@ -197,7 +205,6 @@ class WebSettings {
   virtual void SetMainFrameClipsContent(bool) = 0;
   virtual void SetMainFrameResizesAreOrientationChanges(bool) = 0;
   virtual void SetMaxTouchPoints(int) = 0;
-  virtual void SetMediaPlaybackRequiresUserGesture(bool) = 0;
   virtual void SetMediaPlaybackGestureWhitelistScope(const WebString&) = 0;
   virtual void SetPresentationRequiresUserGesture(bool) = 0;
   virtual void SetEmbeddedMediaExperienceEnabled(bool) = 0;