Prevent ctrl+2f scroll on the touchpad to zoom the page

content/browser/renderer_host/render_widget_host_view_aura.cc

Index: content/browser/renderer_host/render_widget_host_view_aura.cc
diff --git a/content/browser/renderer_host/render_widget_host_view_aura.cc b/content/browser/renderer_host/render_widget_host_view_aura.cc
index 0c14ea8a20901581d3f620354c8ec0e87c26211b..4009334b031935775a3204bc2763c8f43b7ceb37 100644
--- a/content/browser/renderer_host/render_widget_host_view_aura.cc
+++ b/content/browser/renderer_host/render_widget_host_view_aura.cc
@@ -2865,6 +2865,16 @@ void RenderWidgetHostViewAura::OnScrollEvent(ui::ScrollEvent* event) {
     host_->ForwardGestureEvent(gesture_event);
     blink::WebMouseWheelEvent mouse_wheel_event =
         MakeWebMouseWheelEvent(event);
+
+    // We don't want ctrl+two finger scroll to trigger the WebContents zooming
+    // function as it is too sensitive and most people don't expect the effect
+    // (unlike ctrl+mousewheel, which most people expect to zoom the page).
+    // Therefore, we clear the modifier here if and only if the ctrl key is
+    // pressed and no any other key is pressed at the same time. This prevents
+    // WebContentsImpl to zoom the page while retain the scroll event and other

[Daniel Erat, 2013/12/26 14:44:22]

nit: s/to zoom/from zooming/, s/while retain/while retaining/

[Shecky Lin, 2013/12/27 03:23:54]

Done.

+    // modifier combinations in case the webpage might want to use them.
+    if (mouse_wheel_event.modifiers == blink::WebInputEvent::ControlKey)
+      mouse_wheel_event.modifiers = 0;
     host_->ForwardWheelEvent(mouse_wheel_event);
     RecordAction(UserMetricsAction("TrackpadScroll"));
   } else if (event->type() == ui::ET_SCROLL_FLING_START ||