Explicitly suppress scrolling for wheel events that will trigger zooming

content/browser/renderer_host/web_input_event_aura.cc

Index: content/browser/renderer_host/web_input_event_aura.cc
diff --git a/content/browser/renderer_host/web_input_event_aura.cc b/content/browser/renderer_host/web_input_event_aura.cc
index 4fe79c16dd1aae6893132ca789bc567c5449fa50..48679c5373ff5afc47da913edc25b9f6f839f855 100644
--- a/content/browser/renderer_host/web_input_event_aura.cc
+++ b/content/browser/renderer_host/web_input_event_aura.cc
@@ -197,6 +197,14 @@ blink::WebMouseWheelEvent MakeWebMouseWheelEvent(ui::MouseWheelEvent* event) {
   webkit_event.globalX = root_point.x();
   webkit_event.globalY = root_point.y();
 
+  // Scroll events generated from the mouse wheel when the control key is held
+  // don't trigger scrolling. Instead, they may cause zooming.
+  bool from_mouseWheel = !webkit_event.hasPreciseScrollingDeltas;

[tdresser, 2014/12/03 13:45:05]

Sorry, I used the wrong formatting in my comment.

Should be from_mousewheel or from_mouse_wheel.

I think that's a lot clearer now, thanks!

[lanwei, 2014/12/03 22:06:44]

Done.

+  if ((webkit_event.modifiers & blink::WebInputEvent::ControlKey)
+      && from_mouseWheel) {

[jdduke (slow), 2014/12/03 21:37:10]

Nit: The && should be at the end of the preceding line (unlike Java =/).

[lanwei, 2014/12/03 22:06:44]

Done.

Yes, just realize they have different styles.

+    webkit_event.canScroll = false;
+  }
+
   return webkit_event;
 }