Revert 179987

ipc/ipc_sync_channel.h

Index: ipc/ipc_sync_channel.h
===================================================================
--- ipc/ipc_sync_channel.h	(revision 179992)
+++ ipc/ipc_sync_channel.h	(working copy)
@@ -58,7 +58,8 @@
 // is more than this object.  If the message loop goes away while this object
 // is running and it's used to send a message, then it will use the invalid
 // message loop pointer to proxy it to the ipc thread.
-class IPC_EXPORT SyncChannel : public ChannelProxy {
+class IPC_EXPORT SyncChannel : public ChannelProxy,
+                               public base::WaitableEventWatcher::Delegate {
  public:
   enum RestrictDispatchGroup {
     kRestrictDispatchGroup_None = 0,
@@ -114,7 +115,8 @@
   // SyncContext holds the per object data for SyncChannel, so that SyncChannel
   // can be deleted while it's being used in a different thread.  See
   // ChannelProxy::Context for more information.
-  class SyncContext : public Context {
+  class SyncContext : public Context,
+                      public base::WaitableEventWatcher::Delegate {
    public:
     SyncContext(Listener* listener,
                 base::SingleThreadTaskRunner* ipc_task_runner,
@@ -148,10 +150,6 @@
     void OnSendTimeout(int message_id);
 
     base::WaitableEvent* shutdown_event() { return shutdown_event_; }
-    base::WaitableEventWatcher::EventCallback
-        shutdown_watcher_callback() const {
-      return shutdown_watcher_callback_;
-    }
 
     ReceivedSyncMsgQueue* received_sync_msgs() {
       return received_sync_msgs_;
@@ -181,7 +179,8 @@
     // Cancels all pending Send calls.
     void CancelPendingSends();
 
-    void OnWaitableEventSignaled(base::WaitableEvent* arg);
+    // WaitableEventWatcher::Delegate implementation.
+    virtual void OnWaitableEventSignaled(base::WaitableEvent* arg) OVERRIDE;
 
     typedef std::deque<PendingSyncMsg> PendingSyncMessageQueue;
     PendingSyncMessageQueue deserializers_;
@@ -191,12 +190,12 @@
 
     base::WaitableEvent* shutdown_event_;
     base::WaitableEventWatcher shutdown_watcher_;
-    base::WaitableEventWatcher::EventCallback shutdown_watcher_callback_;
     int restrict_dispatch_group_;
   };
 
  private:
-  void OnWaitableEventSignaled(base::WaitableEvent* arg);
+  // WaitableEventWatcher::Delegate implementation.
+  virtual void OnWaitableEventSignaled(base::WaitableEvent* arg) OVERRIDE;
 
   SyncContext* sync_context() {
     return reinterpret_cast<SyncContext*>(context());
@@ -218,7 +217,6 @@
 
   // Used to signal events between the IPC and listener threads.
   base::WaitableEventWatcher dispatch_watcher_;
-  base::Callback<void(base::WaitableEvent*)> dispatch_watcher_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncChannel);
 };