Makes wait-for-debugger=content_browser work for mash

chrome/app/chrome_main.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 <stdint.h>
 
 #include "build/build_config.h"
 #include "base/time/time.h"
 #include "chrome/app/chrome_main_delegate.h"
 #include "chrome/common/features.h"
@@ skipping 76 matching lines @@
   base::CommandLine::Init(params.argc, params.argv);
 #endif
 
   version_info::Channel channel = chrome::GetChannel();
   if (channel == version_info::Channel::CANARY ||
       channel == version_info::Channel::UNKNOWN) {
     const base::CommandLine& command_line =
         *base::CommandLine::ForCurrentProcess();
     if (command_line.HasSwitch("mash"))
       return MashMain();
+    WaitForMashDebuggerIfNecessary();
   }
 #endif  // BUILDFLAG(ENABLE_PACKAGE_MASH_SERVICES)
 
   int rv = content::ContentMain(params);
 
 #if defined(OS_WIN)
   base::win::SetShouldCrashOnProcessDetach(false);
 #endif
 
   return rv;
 }