Add -ifsameorigin to autoplay experiment.

third_party/WebKit/Source/core/frame/Frame.h

Index: third_party/WebKit/Source/core/frame/Frame.h
diff --git a/third_party/WebKit/Source/core/frame/Frame.h b/third_party/WebKit/Source/core/frame/Frame.h
index 8554f00633424e0ebf8f39dc43d0bef64885d663..378081899a01cdd49fbc9c1b4a5f577c84750dbb 100644
--- a/third_party/WebKit/Source/core/frame/Frame.h
+++ b/third_party/WebKit/Source/core/frame/Frame.h
@@ -121,6 +121,10 @@ public:
 
     Settings* settings() const; // can be null
 
+    // Return true if and only if this frame is a cross-origin frame with
+    // respect to the top-level frame.
+    bool isCrossOrigin() const;

[dcheng, 2016/05/05 23:14:50]

Sorry for missing this... I've updated my WATCHLISTS.

Can we rename this to be clearer? Something like isCrossOriginToMainFrame(). I
know it's in the comment, but it's not at all clear in the call sites.

+
     // isLoading() is true when the embedder should think a load is in progress.
     // In the case of LocalFrames, it means that the frame has sent a didStartLoading()
     // callback, but not the matching didStopLoading(). Inside blink, you probably