Make mojo::system::Core not own the PlatformSupport.

mojo/edk/embedder/embedder_internal.h

 // 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.
 
 // This header contains internal details for the *implementation* of the
 // embedder API. It should not be included by any public header (nor by users of
 // the embedder API).
 
 #ifndef MOJO_EDK_EMBEDDER_EMBEDDER_INTERNAL_H_
 #define MOJO_EDK_EMBEDDER_EMBEDDER_INTERNAL_H_
 
 #include <stdint.h>
 
 namespace mojo {
 
 namespace system {
 
 class ChannelManager;
 class Core;
 
 // Repeat a typedef in mojo/edk/system/channel_manager.h, to avoid including it.
 typedef uint64_t ChannelId;
 
 }  // namespace system
 
 namespace embedder {
 
+class PlatformSupport;
+
 // This is a type that's opaque to users of the embedder API (which only
 // gives/takes |ChannelInfo*|s). We make it a struct to make it
 // template-friendly.
 struct ChannelInfo {
   explicit ChannelInfo(system::ChannelId channel_id = 0)
       : channel_id(channel_id) {}
 
   system::ChannelId channel_id;
 };
 
 namespace internal {
 
+// Instance of |PlatformSupport| to use.
+extern PlatformSupport* g_platform_support;
+
 // Instance of |Core| used by the system functions (|Mojo...()|).
 extern system::Core* g_core;
 
 // Instance of |ChannelManager| used by the channel management functions
 // (|mojo::embedder::CreateChannel()|, etc.).
 extern system::ChannelManager* g_channel_manager;
 
 }  // namespace internal
 
 }  // namepace embedder
 
 }  // namespace mojo
 
 #endif  // MOJO_EDK_EMBEDDER_EMBEDDER_INTERNAL_H_