Move shell service to toplevel shell namespace

services/shell/background/background_shell_main.cc

 // Copyright 2016 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 "services/shell/background/background_shell_main.h"
 
 #include "base/at_exit.h"
 #include "base/command_line.h"
 #include "base/debug/debugger.h"
 #include "base/process/launch.h"
 #include "services/shell/runner/common/switches.h"
 #include "services/shell/runner/host/child_process.h"
 #include "services/shell/runner/init.h"
 
-namespace mojo {
 namespace shell {
 namespace {
 
 int RunChildProcess() {
   base::AtExitManager at_exit;
   InitializeLogging();
   WaitForDebuggerIfNecessary();
 #if !defined(OFFICIAL_BUILD) && defined(OS_WIN)
   base::RouteStdioToConsole(false);
 #endif
   return ChildProcessMain();
 }
 
 }  // namespace
 }  // namespace shell
-}  // namespace mojo
 
 int main(int argc, char** argv) {
   base::CommandLine::Init(argc, argv);
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kChildProcess)) {
-    return mojo::shell::RunChildProcess();
+    return shell::RunChildProcess();
   }
   // Reset CommandLine as most likely main() is going to use CommandLine too
   // and expect to be able to initialize it.
   base::CommandLine::Reset();
   return MasterProcessMain(argc, argv);
 }