Notify Blink about start of gesture scroll through a queued event.

third_party/WebKit/Source/web/WebInputEventConversion.cpp

Index: third_party/WebKit/Source/web/WebInputEventConversion.cpp
diff --git a/third_party/WebKit/Source/web/WebInputEventConversion.cpp b/third_party/WebKit/Source/web/WebInputEventConversion.cpp
index b020b0fefe2505da660ce60447e3fab4555fcdfd..cb365e102de935bc9961cfa352bae245de12dd87 100644
--- a/third_party/WebKit/Source/web/WebInputEventConversion.cpp
+++ b/third_party/WebKit/Source/web/WebInputEventConversion.cpp
@@ -393,6 +393,8 @@ inline PlatformEvent::EventType toPlatformTouchEventType(const WebInputEvent::Ty
         return PlatformEvent::TouchEnd;
     case WebInputEvent::TouchCancel:
         return PlatformEvent::TouchCancel;
+    case WebInputEvent::TouchScrollStarted:
+        return PlatformEvent::TouchScrollStarted;
     default:
         NOTREACHED();
     }