IPC: Fix attachment brokering race condition.

content/common/child_process_host_impl.cc

Index: content/common/child_process_host_impl.cc
diff --git a/content/common/child_process_host_impl.cc b/content/common/child_process_host_impl.cc
index e9b81e75f9d894f99bc530a4fbe79bf8c9609dff..1aa93b529873b9e7d342ad3e3f955ac36638385f 100644
--- a/content/common/child_process_host_impl.cc
+++ b/content/common/child_process_host_impl.cc
@@ -133,12 +133,17 @@ void ChildProcessHostImpl::ForceShutdown() {
 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(), base::MessageLoopForIO::current()->task_runner());
 #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());