Mark sub-frame root layer non-fast scrollable when wheel handlers present.

content/renderer/gpu/render_widget_compositor.cc

 // Copyright (c) 2013 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/renderer/gpu/render_widget_compositor.h"
 
 #include <stddef.h>
 
 #include <cmath>
 #include <limits>
@@ skipping 811 matching lines @@
               "EventListener and WebEventListener enums must match");
 
 void RenderWidgetCompositor::setEventListenerProperties(
     blink::WebEventListenerClass eventClass,
     blink::WebEventListenerProperties properties) {
   layer_tree_host_->SetEventListenerProperties(
       static_cast<cc::EventListenerClass>(eventClass),
       static_cast<cc::EventListenerProperties>(properties));
 }
 
-void RenderWidgetCompositor::updateTouchRectsForSubframeIfNecessary() {
+void RenderWidgetCompositor::updateEventRectsForSubframeIfNecessary() {
   if (!is_for_oopif_)
     return;
 
   // If this is an oopif sub-frame compositor, we won't be getting TouchRects
   // from ScrollingCoordinator, so to make sure touch events are handled
   // properly, mark the entire root layer as a TouchRect.
   // TODO(wjmaclean): remove this when ScrollingCoordinator is made per-frame,
   // as opposed to per-page.
   using blink::WebEventListenerProperties;
   using blink::WebEventListenerClass;
 
-  blink::WebEventListenerProperties touch_start_properties =
+  WebEventListenerProperties touch_start_properties =
       eventListenerProperties(WebEventListenerClass::TouchStartOrMove);
-  blink::WebEventListenerProperties touch_end_cancel_properties =
+  WebEventListenerProperties touch_end_cancel_properties =
       eventListenerProperties(WebEventListenerClass::TouchEndOrCancel);
   bool has_touch_handlers =
       touch_start_properties == WebEventListenerProperties::Blocking ||
       touch_start_properties ==
           WebEventListenerProperties::BlockingAndPassive ||
       touch_end_cancel_properties == WebEventListenerProperties::Blocking ||
       touch_end_cancel_properties ==
           WebEventListenerProperties::BlockingAndPassive;
 
+  WebEventListenerProperties wheel_event_properties =
+      eventListenerProperties(WebEventListenerClass::MouseWheel);
+  bool has_wheel_handlers =
+      wheel_event_properties == WebEventListenerProperties::Blocking ||
+      wheel_event_properties == WebEventListenerProperties::BlockingAndPassive;
+
   cc::Layer* root_layer = layer_tree_host_->root_layer();
   cc::Region touch_handler_region;
   if (has_touch_handlers)
     touch_handler_region = gfx::Rect(gfx::Point(), root_layer->bounds());
   root_layer->SetTouchEventHandlerRegion(touch_handler_region);
+
+  cc::Region wheel_handler_region;
+  if (has_wheel_handlers)
+    wheel_handler_region = gfx::Rect(gfx::Point(), root_layer->bounds());
+  root_layer->SetNonFastScrollableRegion(wheel_handler_region);
 }
 
 blink::WebEventListenerProperties
 RenderWidgetCompositor::eventListenerProperties(
     blink::WebEventListenerClass event_class) const {
   return static_cast<blink::WebEventListenerProperties>(
       layer_tree_host_->event_listener_properties(
           static_cast<cc::EventListenerClass>(event_class)));
 }
 
@@ skipping 257 matching lines @@
 
 void RenderWidgetCompositor::SetIsForOopif(bool is_for_oopif) {
   is_for_oopif_ = is_for_oopif;
 }
 
 void RenderWidgetCompositor::SetContentSourceId(uint32_t id) {
   layer_tree_host_->SetContentSourceId(id);
 }
 
 }  // namespace content