Make zoom using ctrl+mouse wheel work in win aura. Windows -non-aura had a hack that was a layering…

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 <utility>
 
 #include "base/auto_reset.h"
@@ skipping 923 matching lines @@
 
 void RenderWidgetHostImpl::OnPointerEventActivate() {
 }
 
 void RenderWidgetHostImpl::ForwardWheelEvent(
     const WebMouseWheelEvent& wheel_event) {
   TRACE_EVENT0("renderer_host", "RenderWidgetHostImpl::ForwardWheelEvent");
   if (ignore_input_events_ || process_->IgnoreInputEvents())
     return;
 
+  if (delegate_->PreHandleWheelEvent(wheel_event))
+    return;
+
   // If there's already a mouse wheel event waiting to be sent to the renderer,
   // add the new deltas to that event. Not doing so (e.g., by dropping the old
   // event, as for mouse moves) results in very slow scrolling on the Mac (on
   // which many, very small wheel events are sent).
   if (mouse_wheel_pending_) {
     if (coalesced_mouse_wheel_events_.empty() ||
         !ShouldCoalesceMouseWheelEvents(coalesced_mouse_wheel_events_.back(),
                                         wheel_event)) {
       coalesced_mouse_wheel_events_.push_back(wheel_event);
     } else {
@@ skipping 1437 matching lines @@
     return;
 
   OnRenderAutoResized(new_size);
 }
 
 void RenderWidgetHostImpl::DetachDelegate() {
   delegate_ = NULL;
 }
 
 }  // namespace content