Explicitly suppress scrolling for wheel events that will trigger zooming

content/browser/renderer_host/input/input_router_impl.cc

Index: content/browser/renderer_host/input/input_router_impl.cc
diff --git a/content/browser/renderer_host/input/input_router_impl.cc b/content/browser/renderer_host/input/input_router_impl.cc
index 4848f6dc6f41075434b458e3baa78175298962aa..7c10c41c063c38ca0b8136e1b9ffc36205741644 100644
--- a/content/browser/renderer_host/input/input_router_impl.cc
+++ b/content/browser/renderer_host/input/input_router_impl.cc
@@ -457,7 +457,8 @@ void InputRouterImpl::SendSyntheticWheelEventForPinch(
   wheelEvent.wheelTicksX = 0;
   wheelEvent.wheelTicksY =
       pinch_event.event.data.pinchUpdate.scale > 1 ? 1 : -1;
-
+  // Avoid touchpad pinch on Mac OS to scroll.

[tdresser, 2014/12/02 15:37:37]

Is this Mac OS specific?

Reword to:
Prevent trackpad pinch from scrolling.
OR
Prevent trackpad pinch from scrolling on Mac OS.

[lanwei, 2014/12/02 22:28:06]

Done.

Yes, this is only for Mac OS.

+  wheelEvent.canScroll = false;
   SendWheelEvent(QueuedWheelEvent(
       MouseWheelEventWithLatencyInfo(wheelEvent, pinch_event.latency), true));
 }