Always use ChannelMojo for content child processes.

content/common/child_process_host_impl.h

 // 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.
 
 #ifndef CONTENT_COMMON_CHILD_PROCESS_HOST_IMPL_H_
 #define CONTENT_COMMON_CHILD_PROCESS_HOST_IMPL_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 60 matching lines @@
   // process.
   //
   // Never returns MemoryDumpManager::kInvalidTracingProcessId.
   // Returns only ChildProcessHost::kBrowserTracingProcessId in single-process
   // mode.
   static uint64_t ChildProcessUniqueIdToTracingProcessId(int child_process_id);
 
   // ChildProcessHost implementation
   bool Send(IPC::Message* message) override;
   void ForceShutdown() override;
-  std::string CreateChannel() override;
   std::string CreateChannelMojo(const std::string& child_token) override;
   void CreateChannelMojo() override;
   bool IsChannelOpening() override;
   void AddFilter(IPC::MessageFilter* filter) override;
   shell::InterfaceProvider* GetRemoteInterfaces() override;
 #if defined(OS_POSIX)
   base::ScopedFD TakeClientFileDescriptor() override;
 #endif
 
  private:
@@ skipping 34 matching lines @@
   // thread, we don't have a IPC::ChannelProxy and so we manage filters
   // manually.
   std::vector<scoped_refptr<IPC::MessageFilter> > filters_;
 
   DISALLOW_COPY_AND_ASSIGN(ChildProcessHostImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_CHILD_PROCESS_HOST_IMPL_H_