Use WaitableEvents to wake up sync IPC waiting

ipc/ipc_sync_message_filter.h

 // 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.
 
 #ifndef IPC_IPC_SYNC_MESSAGE_FILTER_H_
 #define IPC_IPC_SYNC_MESSAGE_FILTER_H_
 
 #include <set>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/memory/weak_ptr.h"
 #include "base/synchronization/lock.h"
-#include "base/synchronization/waitable_event_watcher.h"
 #include "ipc/ipc_sender.h"
 #include "ipc/ipc_sync_message.h"
 #include "ipc/message_filter.h"
-#include "ipc/mojo_event.h"
 #include "mojo/public/cpp/bindings/associated_interface_ptr.h"
 #include "mojo/public/cpp/bindings/associated_interface_request.h"
 #include "mojo/public/cpp/bindings/scoped_interface_endpoint_handle.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 class WaitableEvent;
 }
 
 namespace IPC {
@@ skipping 26 matching lines @@
       mojo::AssociatedInterfacePtr<Interface>* proxy) {
     auto request = mojo::MakeRequest(proxy);
     GetGenericRemoteAssociatedInterface(Interface::Name_, request.PassHandle());
   }
 
  protected:
   explicit SyncMessageFilter(base::WaitableEvent* shutdown_event);
   ~SyncMessageFilter() override;
 
  private:
-  class IOMessageLoopObserver;
-
   friend class SyncChannel;
-  friend class IOMessageLoopObserver;
 
   void SendOnIOThread(Message* message);
   // Signal all the pending sends as done, used in an error condition.
   void SignalAllEvents();
 
-  void OnShutdownEventSignaled(base::WaitableEvent* event);
-  void OnIOMessageLoopDestroyed();
-
   // NOTE: This must ONLY be called on the Channel's thread.
   void GetGenericRemoteAssociatedInterface(
       const std::string& interface_name,
       mojo::ScopedInterfaceEndpointHandle handle);
 
   // The channel to which this filter was added.
   Channel* channel_;
 
   // The process's main thread.
   scoped_refptr<base::SingleThreadTaskRunner> listener_task_runner_;
 
   // The message loop where the Channel lives.
   scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
 
   typedef std::set<PendingSyncMsg*> PendingSyncMessages;
   PendingSyncMessages pending_sync_messages_;
 
   // Messages waiting to be delivered after IO initialization.
   std::vector<std::unique_ptr<Message>> pending_messages_;
 
   // Locks data members above.
   base::Lock lock_;
 
   base::WaitableEvent* const shutdown_event_;
 
-  // Used to asynchronously watch |shutdown_event_| on the IO thread and forward
-  // to |shutdown_mojo_event_| (see below.)
-  base::WaitableEventWatcher shutdown_watcher_;
-
-  // A Mojo event which can be watched for shutdown. Signals are forwarded to
-  // this event asynchronously from |shutdown_event_|.
-  MojoEvent shutdown_mojo_event_;
-
-  scoped_refptr<IOMessageLoopObserver> io_message_loop_observer_;
-
-  base::WeakPtrFactory<SyncMessageFilter> weak_factory_;
-
   DISALLOW_COPY_AND_ASSIGN(SyncMessageFilter);
 };
 
 }  // namespace IPC
 
 #endif  // IPC_IPC_SYNC_MESSAGE_FILTER_H_