use enum to specify deviceSource for fling animation

public/platform/WebGestureDevice.h

Index: public/platform/WebGestureDevice.h
diff --git a/public/platform/WebRenderingStats.h b/public/platform/WebGestureDevice.h
similarity index 85%
copy from public/platform/WebRenderingStats.h
copy to public/platform/WebGestureDevice.h
index ddd117af127a2a0117044dc1a687790ebab6b41c..41b8856c33ead8a53fa0fe2346f1bd0d24dce0c5 100644
--- a/public/platform/WebRenderingStats.h
+++ b/public/platform/WebGestureDevice.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012 Google Inc. All rights reserved.
+ * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -23,17 +23,16 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef WebRenderingStats_h
-#define WebRenderingStats_h
+#ifndef WebGestureDevice_h
+#define WebGestureDevice_h
 
 namespace blink {
 
-struct WebRenderingStats {
-    WebRenderingStats()
-    {
-    }
+enum WebGestureDevice {
+    WebGestureDeviceTouchpad,
+    WebGestureDeviceTouchscreen,
 };
 
 } // namespace blink
 
-#endif // WebRenderingStats_h
+#endif // WebGestureDevice_h