Explicitly suppress scrolling for wheel events that will trigger zooming

content/browser/web_contents/web_contents_impl.cc

Index: content/browser/web_contents/web_contents_impl.cc
diff --git a/content/browser/web_contents/web_contents_impl.cc b/content/browser/web_contents/web_contents_impl.cc
index e6f8713fdb8985d0631ca19b12868461d106921c..e4cf3de3bec56df345321fe72d2fe5be3f80b329 100644
--- a/content/browser/web_contents/web_contents_impl.cc
+++ b/content/browser/web_contents/web_contents_impl.cc
@@ -1325,8 +1325,8 @@ void WebContentsImpl::HandleKeyboardEvent(const NativeWebKeyboardEvent& event) {
 bool WebContentsImpl::HandleWheelEvent(
     const blink::WebMouseWheelEvent& event) {
 #if !defined(OS_MACOSX)
-  // On platforms other than Mac, control+mousewheel changes zoom. On Mac, this
-  // isn't done for two reasons:
+  // On platforms other than Mac, control+mousewheel may changes zoom. On Mac,

[tdresser, 2014/12/02 15:37:38]

may changes -> may change

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

Done.

+  // this isn't done for two reasons:
   //   -the OS already has a gesture to do this through pinch-zoom
   //   -if a user starts an inertial scroll, let's go, and presses control
   //      (i.e. control+tab) then the OS's buffered scroll events will come in
@@ -1334,9 +1334,7 @@ bool WebContentsImpl::HandleWheelEvent(
   if (delegate_ &&
       event.wheelTicksY &&
       (event.modifiers & blink::WebInputEvent::ControlKey) &&
-      // Avoid adjusting the zoom in response to two-finger-scrolling touchpad
-      // gestures, which are regrettably easy to trigger accidentally.
-      !event.hasPreciseScrollingDeltas) {
+      !event.canScroll) {
     delegate_->ContentsZoomChange(event.wheelTicksY > 0);
     return true;
   }