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 c4a766a8d1e3191c298ce3e329fbb64892bbec20..76bdbf13493d80ef3e582ec751ee53a3dca8948f 100644
--- a/content/browser/renderer_host/web_input_event_aura.cc
+++ b/content/browser/renderer_host/web_input_event_aura.cc
@@ -193,14 +193,23 @@ blink::WebMouseWheelEvent MakeWebMouseWheelEvent(
   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_mouse_wheel = !webkit_event.hasPreciseScrollingDeltas;
+  if ((webkit_event.modifiers & blink::WebInputEvent::ControlKey) &&
+      from_mouse_wheel) {
+    webkit_event.canScroll = false;
+  }
+
   return webkit_event;
 }
 
 blink::WebMouseWheelEvent MakeWebMouseWheelEvent(const ui::ScrollEvent& event) {
 #if defined(OS_WIN)
   // Construct an untranslated event from the platform event data.
-  blink::WebMouseWheelEvent webkit_event =
-      MakeUntranslatedWebMouseWheelEventFromNativeEvent(event.native_event());
+  blink::WebMouseWheelEvent webkit_event = event.native_event().message ?
+      MakeUntranslatedWebMouseWheelEventFromNativeEvent(event.native_event()) :
+      MakeWebMouseWheelEventFromAuraEvent(event);
 #else
   blink::WebMouseWheelEvent webkit_event =
       MakeWebMouseWheelEventFromAuraEvent(event);