[Merge to M50] IPC: Fix attachment brokering race condition.

content/common/child_process_host_impl.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 "content/common/child_process_host_impl.h"
 
 #include <limits>
 
 #include "base/atomic_sequence_num.h"
 #include "base/command_line.h"
@@ skipping 114 matching lines @@
     filter->OnFilterAdded(channel_.get());
 }
 
 void ChildProcessHostImpl::ForceShutdown() {
   Send(new ChildProcessMsg_Shutdown());
 }
 
 std::string ChildProcessHostImpl::CreateChannel() {
   channel_id_ = IPC::Channel::GenerateVerifiedChannelID(std::string());
   channel_ = IPC::Channel::CreateServer(channel_id_, this);
-  if (!channel_->Connect())
-    return std::string();
 #if USE_ATTACHMENT_BROKER
   IPC::AttachmentBroker::GetGlobal()->RegisterCommunicationChannel(
       channel_.get());
 #endif
+  if (!channel_->Connect()) {
+#if USE_ATTACHMENT_BROKER
+    IPC::AttachmentBroker::GetGlobal()->DeregisterCommunicationChannel(
+        channel_.get());
+#endif
+    return std::string();
+  }
 
   for (size_t i = 0; i < filters_.size(); ++i)
     filters_[i]->OnFilterAdded(channel_.get());
 
   // Make sure these messages get sent first.
 #if defined(IPC_MESSAGE_LOG_ENABLED)
   bool enabled = IPC::Logging::GetInstance()->Enabled();
   Send(new ChildProcessMsg_SetIPCLoggingEnabled(enabled));
 #endif
 
@@ skipping 172 matching lines @@
 }
 
 void ChildProcessHostImpl::OnDeletedGpuMemoryBuffer(
     gfx::GpuMemoryBufferId id,
     const gpu::SyncToken& sync_token) {
   // Note: Nothing to do here as ownership of shared memory backed
   // GpuMemoryBuffers is passed with IPC.
 }
 
 }  // namespace content