Give blink a chance to consume ctrl+wheel events before zooming

content/browser/renderer_host/render_widget_host_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/renderer_host/render_widget_host_impl.h"
 
 #include <math.h>
 #include <set>
 #include <utility>
 
@@ skipping 955 matching lines @@
       const blink::WebMouseWheelEvent& wheel_event,
       const ui::LatencyInfo& ui_latency) {
   TRACE_EVENT0("input", "RenderWidgetHostImpl::ForwardWheelEvent");
 
   ui::LatencyInfo latency_info =
       CreateRWHLatencyInfoIfNotExist(&ui_latency, wheel_event.type);
 
   if (IgnoreInputEvents())
     return;
 
-  if (delegate_->PreHandleWheelEvent(wheel_event))
-    return;
-
   input_router_->SendWheelEvent(MouseWheelEventWithLatencyInfo(wheel_event,
                                                                latency_info));
 }
 
 void RenderWidgetHostImpl::ForwardGestureEvent(
     const blink::WebGestureEvent& gesture_event) {
   ForwardGestureEventWithLatencyInfo(gesture_event, ui::LatencyInfo());
 }
 
 void RenderWidgetHostImpl::ForwardGestureEventWithLatencyInfo(
@@ skipping 1066 matching lines @@
   if (!wheel_event.latency.FindLatency(
           ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_COMPONENT, 0, NULL)) {
     // MouseWheelEvent latency ends when it is acked but does not cause any
     // rendering scheduled.
     ui::LatencyInfo latency = wheel_event.latency;
     latency.AddLatencyNumber(
         ui::INPUT_EVENT_LATENCY_TERMINATED_MOUSE_COMPONENT, 0, 0);
   }
 
   const bool processed = (INPUT_EVENT_ACK_STATE_CONSUMED == ack_result);
-  if (!processed && !is_hidden() && view_)
-    view_->UnhandledWheelEvent(wheel_event.event);
+  if (!processed && !is_hidden() && view_) {
+    if (!delegate_->HandleWheelEvent(wheel_event.event))
+      view_->UnhandledWheelEvent(wheel_event.event);
+  }
 }
 
 void RenderWidgetHostImpl::OnGestureEventAck(
     const GestureEventWithLatencyInfo& event,
     InputEventAckState ack_result) {
   if (!event.latency.FindLatency(
           ui::INPUT_EVENT_LATENCY_RENDERING_SCHEDULED_COMPONENT, 0, NULL)) {
     // GestureEvent latency ends when it is acked but does not cause any
     // rendering scheduled.
     ui::LatencyInfo latency = event.latency;
@@ skipping 465 matching lines @@
     }
   }
 
   // Add newly generated components into the latency info
   for (lc = new_components.begin(); lc != new_components.end(); ++lc) {
     latency_info->latency_components[lc->first] = lc->second;
   }
 }
 
 }  // namespace content