Make it possible for the scroll offset delegate to intercept fling.

content/browser/renderer_host/render_widget_host_view_android.cc

Index: content/browser/renderer_host/render_widget_host_view_android.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_android.cc b/content/browser/renderer_host/render_widget_host_view_android.cc
index 806f35ff2fc5e6e4a10c1d38363f3e69992e3887..61388f9a2adffef890e999feceb4905d7dad119f 100644
--- a/content/browser/renderer_host/render_widget_host_view_android.cc
+++ b/content/browser/renderer_host/render_widget_host_view_android.cc
@@ -864,6 +864,15 @@ void RenderWidgetHostViewAndroid::UnhandledWheelEvent(
   // intentionally empty, like RenderWidgetHostViewViews
 }
 
+void RenderWidgetHostViewAndroid::GestureEventAck(
+    int gesture_event_type,
+    InputEventAckState ack_result) {
+  if (gesture_event_type == WebKit::WebInputEvent::GestureFlingStart &&
+      ack_result == INPUT_EVENT_ACK_STATE_NO_CONSUMER_EXISTS) {
+    content_view_core_->UnhandledFlingStartEvent();
+  }
+}
+
 InputEventAckState RenderWidgetHostViewAndroid::FilterInputEvent(
     const WebKit::WebInputEvent& input_event) {
   if (host_) {