Make cc::SurfaceId unguessable

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 <set>
 #include <utility>
 
 #include "base/auto_reset.h"
@@ skipping 2044 matching lines @@
       gfx::ConvertPointToPixel(device_scale_factor_, point);
   cc::SurfaceId id = delegated_frame_host_->SurfaceIdAtPoint(
       delegate, point_in_pixels, transformed_point);
   *transformed_point =
       gfx::ConvertPointToDIP(device_scale_factor_, *transformed_point);
 
   // It is possible that the renderer has not yet produced a surface, in which
   // case we return our current namespace.
   if (id.is_null())
     return GetSurfaceIdNamespace();
-  return cc::SurfaceIdAllocator::NamespaceForId(id);
+  return id.id_namespace();
 }
 
 void RenderWidgetHostViewAura::ProcessMouseEvent(
     const blink::WebMouseEvent& event) {
   host_->ForwardMouseEvent(event);
 }
 
 void RenderWidgetHostViewAura::ProcessMouseWheelEvent(
     const blink::WebMouseWheelEvent& event) {
   host_->ForwardWheelEvent(event);
@@ skipping 917 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // RenderWidgetHostViewBase, public:
 
 // static
 void RenderWidgetHostViewBase::GetDefaultScreenInfo(WebScreenInfo* results) {
   GetScreenInfoForWindow(results, NULL);
 }
 
 }  // namespace content