Handle mac trackpad zoom via GesturePinch events

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 2102 matching lines @@
     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;
     latency.AddLatencyNumber(
         ui::INPUT_EVENT_LATENCY_TERMINATED_GESTURE_COMPONENT, 0 ,0);
   }
 
+  if (ack_result != INPUT_EVENT_ACK_STATE_CONSUMED) {
+    if (delegate_->HandleGestureEvent(event.event))
+      ack_result = INPUT_EVENT_ACK_STATE_CONSUMED;
+  }
+
   if (view_)
     view_->GestureEventAck(event.event, ack_result);
 }
 
 void RenderWidgetHostImpl::OnTouchEventAck(
     const TouchEventWithLatencyInfo& event,
     InputEventAckState ack_result) {
   TouchEventWithLatencyInfo touch_event = event;
   touch_event.latency.AddLatencyNumber(
       ui::INPUT_EVENT_LATENCY_ACKED_TOUCH_COMPONENT, 0, 0);
@@ skipping 399 matching lines @@
   }
 }
 
 SkBitmap::Config RenderWidgetHostImpl::PreferredReadbackFormat() {
   if (view_)
     return view_->PreferredReadbackFormat();
   return SkBitmap::kARGB_8888_Config;
 }
 
 }  // namespace content