Some touch-event forwarding optimization.

content/browser/renderer_host/render_widget_host_view_aura.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_view_aura.h"
 
 #include "base/logging.h"
 #include "content/browser/renderer_host/backing_store_skia.h"
 #include "content/browser/renderer_host/render_widget_host.h"
 #include "content/browser/renderer_host/web_input_event_aura.h"
@@ skipping 875 matching lines @@
   // Return true so that we receive released/drag events.
   return true;
 }
 
 ui::TouchStatus RenderWidgetHostViewAura::OnTouchEvent(
     aura::TouchEvent* event) {
   // Update the touch event first.
   WebKit::WebTouchPoint* point = content::UpdateWebTouchEvent(event,
       &touch_event_);
 
-  // Forward the touch event only if a touch point was updated.
-  if (point) {
+  // Forward the touch event only if a touch point was updated, and there's a
+  // touch-event handler in the page.
+  if (point && host_->has_touch_handler()) {
     host_->ForwardTouchEvent(touch_event_);
     UpdateWebTouchEventAfterDispatch(&touch_event_, point);
     return DecideTouchStatus(touch_event_, point);
   }
 
   return ui::TOUCH_STATUS_UNKNOWN;
 }
 
 ui::GestureStatus RenderWidgetHostViewAura::OnGestureEvent(
     aura::GestureEvent* event) {
@@ skipping 179 matching lines @@
 // static
 void RenderWidgetHostView::GetDefaultScreenInfo(
     WebKit::WebScreenInfo* results) {
   const gfx::Size size = gfx::Screen::GetPrimaryMonitorSize();
   results->rect = WebKit::WebRect(0, 0, size.width(), size.height());
   results->availableRect = results->rect;
   // TODO(derat): Don't hardcode this?
   results->depth = 24;
   results->depthPerComponent = 8;
 }