Use kRenderClientId command line flag when starting a render process

content/public/renderer/render_thread.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_PUBLIC_RENDERER_RENDER_THREAD_H_
 #define CONTENT_PUBLIC_RENDERER_RENDER_THREAD_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 88 matching lines @@
   // Post task to all worker threads. Returns number of workers.
   virtual int PostTaskToAllWebWorkers(const base::Closure& closure) = 0;
 
   // Resolve the proxy servers to use for a given url. On success true is
   // returned and |proxy_list| is set to a PAC string containing a list of
   // proxy servers.
   virtual bool ResolveProxy(const GURL& url, std::string* proxy_list) = 0;
 
   // Gets the shutdown event for the process.
   virtual base::WaitableEvent* GetShutdownEvent() = 0;
+
+  // Retrieve the process ID of the browser process.
+  virtual int32_t GetClientId() = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_RENDERER_RENDER_THREAD_H_