Explicitly suppress scrolling for wheel events that will trigger zooming

content/renderer/input/input_handler_proxy.cc

Index: content/renderer/input/input_handler_proxy.cc
diff --git a/content/renderer/input/input_handler_proxy.cc b/content/renderer/input/input_handler_proxy.cc
index 21f3359f90736ba35e32a8f552cf8add554352d3..ae843e07fe0e68dd61fb0341bc12c263f8329868 100644
--- a/content/renderer/input/input_handler_proxy.cc
+++ b/content/renderer/input/input_handler_proxy.cc
@@ -293,7 +293,7 @@ InputHandlerProxy::EventDisposition InputHandlerProxy::HandleMouseWheel(
     // TODO(jamesr): We don't properly handle scroll by page in the compositor
     // thread, so punt it to the main thread. http://crbug.com/236639
     result = DID_NOT_HANDLE;
-  } else if (wheel_event.modifiers & WebInputEvent::ControlKey) {
+  } else if (wheel_event.suppressScroll) {
     // Wheel events involving the control key never trigger scrolling, only

[Rick Byers, 2014/11/27 17:31:32]

Update this comment since it's no longer true - control key sometimes triggers
scrolling now :-)

Note that ideally we'd probably only forward to main when we know there's a
wheel handler (eg. maybe we could still do the ScrollBegin below, just disable
the call to ScrollBy).  But Ctrl+Wheel is rare enough, I'm not too worried about
optimizing it's performance.

[lanwei, 2014/12/02 06:28:54]

Done.

     // event handlers.  Forward to the main thread.
     result = DID_NOT_HANDLE;