Make cc::SurfaceId unguessable

mojo/converters/surfaces/surfaces_type_converters.cc

 // Copyright 2014 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 "mojo/converters/surfaces/surfaces_type_converters.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
@@ skipping 246 matching lines @@
     const cc::SurfaceId& input) {
   SurfaceIdPtr id(SurfaceId::New());
   id->local = static_cast<uint32_t>(input.id);
   id->id_namespace = cc::SurfaceIdAllocator::NamespaceForId(input);
   return id;
 }
 
 // static
 cc::SurfaceId TypeConverter<cc::SurfaceId, SurfaceIdPtr>::Convert(
     const SurfaceIdPtr& input) {
-  uint64_t packed_id = input->id_namespace;
-  packed_id <<= 32ull;
-  packed_id |= input->local;
-  return cc::SurfaceId(packed_id);
+  return cc::SurfaceId(input->id_namespace, input->local);
 }
 
 // static
 ColorPtr TypeConverter<ColorPtr, SkColor>::Convert(const SkColor& input) {
   ColorPtr color(Color::New());
   color->rgba = input;
   return color;
 }
 
 // static
@@ skipping 347 matching lines @@
 }
 
 // static
 std::unique_ptr<cc::CompositorFrame>
 TypeConverter<std::unique_ptr<cc::CompositorFrame>,
               CompositorFramePtr>::Convert(const CompositorFramePtr& input) {
   return ConvertToCompositorFrame(input, nullptr);
 }
 
 }  // namespace mojo