Mojo C++ bindings: make SyncHandleRegistry a ref-counted object.

mojo/public/cpp/bindings/lib/sync_handle_watcher.h

 // Copyright 2016 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.
 
 #ifndef MOJO_PUBLIC_CPP_BINDINGS_LIB_SYNC_HANDLE_WATCHER_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_LIB_SYNC_HANDLE_WATCHER_H_
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/threading/thread_checker.h"
@@ skipping 43 matching lines @@
 
   const Handle handle_;
   const MojoHandleSignals handle_signals_;
   SyncHandleRegistry::HandleCallback callback_;
 
   // Whether |handle_| has been registered with SyncHandleRegistry.
   bool registered_;
   // If non-zero, |handle_| should be registered with SyncHandleRegistry.
   size_t register_request_count_;
 
+  scoped_refptr<SyncHandleRegistry> registry_;
+
   scoped_refptr<base::RefCountedData<bool>> destroyed_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncHandleWatcher);
 };
 
 }  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_SYNC_HANDLE_WATCHER_H_