ipc: don't treat replies with the unblock flag set as regular messages

ipc/ipc_sync_channel.cc

 // 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.
 
 #include "ipc/ipc_sync_channel.h"
 
 #include "base/bind.h"
 #include "base/lazy_instance.h"
 #include "base/location.h"
 #include "base/logging.h"
@@ skipping 305 matching lines @@
 }
 
 bool SyncChannel::SyncContext::OnMessageReceived(const Message& msg) {
   // Give the filters a chance at processing this message.
   if (TryFilters(msg))
     return true;
 
   if (TryToUnblockListener(&msg))
     return true;
 
+  if (msg.is_reply()) {
+    received_sync_msgs_->QueueReply(msg, this);
+    return true;
+  }
+
   if (msg.should_unblock()) {
     received_sync_msgs_->QueueMessage(msg, this);
     return true;
   }
 
-  if (msg.is_reply()) {
-    received_sync_msgs_->QueueReply(msg, this);
-    return true;
-  }
-
   return Context::OnMessageReceivedNoFilter(msg);
 }
 
 void SyncChannel::SyncContext::OnChannelError() {
   CancelPendingSends();
   shutdown_watcher_.StopWatching();
   Context::OnChannelError();
 }
 
 void SyncChannel::SyncContext::OnChannelOpened() {
@@ skipping 186 matching lines @@
   // Ideally we only want to watch this object when running a nested message
   // loop.  However, we don't know when it exits if there's another nested
   // message loop running under it or not, so we wouldn't know whether to
   // stop or keep watching.  So we always watch it, and create the event as
   // manual reset since the object watcher might otherwise reset the event
   // when we're doing a WaitMany.
   dispatch_watcher_.StartWatching(sync_context()->GetDispatchEvent(), this);
 }
 
 }  // namespace IPC