Ensure clean up functions of MessageFilter are paired with their initialization functions

ipc/ipc_channel_proxy.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_channel_proxy.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
@@ skipping 194 matching lines @@
   // TODO(pkasting): Remove ScopedTracker below once crbug.com/477117 is fixed.
   tracked_objects::ScopedTracker tracking_profile(
       FROM_HERE_WITH_EXPLICIT_FUNCTION(
           "477117 ChannelProxy::Context::OnChannelClosed"));
   // It's okay for IPC::ChannelProxy::Close to be called more than once, which
   // would result in this branch being taken.
   if (!channel_)
     return;
 
   for (auto& filter : pending_filters_) {
+    filter->OnFilterAdded(nullptr);

[Ken Rockot(use gerrit already), 2016/11/10 00:49:55]

nit: I think it's worth adding a comment here to clarify why all of these are
called.

[tzik, 2016/11/10 06:17:41]

Done.

+    filter->OnChannelConnected(peer_pid_);
     filter->OnChannelClosing();
     filter->OnFilterRemoved();
   }
   for (auto& filter : filters_) {
     filter->OnChannelClosing();
     filter->OnFilterRemoved();
   }
 
   // We don't need the filters anymore.
   message_filter_router_->Clear();
@@ skipping 425 matching lines @@
   return channel->TakeClientFileDescriptor();
 }
 #endif
 
 void ChannelProxy::OnChannelInit() {
 }
 
 //-----------------------------------------------------------------------------
 
 }  // namespace IPC