Add flag for enabling/disabling video fullscreen detection

third_party/WebKit/Source/platform/RuntimeEnabledFeatures.json5

Index: third_party/WebKit/Source/platform/RuntimeEnabledFeatures.json5
diff --git a/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.json5 b/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.json5
index 83b46fef2dbdcc429ba180eacba5958b3a92f266..29551470f64351b82a034bb8e876f5163c451514 100644
--- a/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.json5
+++ b/third_party/WebKit/Source/platform/RuntimeEnabledFeatures.json5
@@ -1030,6 +1030,10 @@
     {
       name: "MediaControlsOverlayPlayButton",
       settable_from_internals: true,
+    },
+    {
+      name: "VideoFullscreenDetection",
+      status: "test",

[mlamouri (slow - plz ping), 2017/03/14 12:02:24]

Can we drop "test"? That would enable it for all LayoutTests. I would prefer us
to turn it on when we want to instead.

[Zhiqiang Zhang (Slow), 2017/03/14 13:15:29]

Done.

     }
   ],
 }