Addressing minor review comments in ExtensionProcessManager...

chrome/browser/extensions/extension_process_manager.h

 // Copyright (c) 2009 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 CHROME_BROWSER_EXTENSIONS_EXTENSION_PROCESS_MANAGER_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_PROCESS_MANAGER_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 29 matching lines @@
 
   // Creates a new UI-less extension instance.  Like CreateView, but not
   // displayed anywhere.
   ExtensionHost* CreateBackgroundHost(Extension* extension, const GURL& url);
 
   // Returns the SiteInstance that the given URL belongs to.
   SiteInstance* GetSiteInstanceForURL(const GURL& url);
 
   // Register an extension process by |extension_id| and specifying which
   // |process_id| it belongs to.
-  void RegisterExtensionProcess(std::string extension_id, int process_id);
+  void RegisterExtensionProcess(const std::string& extension_id,
+                                int process_id);
 
   // Unregister an extension process with specified |process_id|.
   void UnregisterExtensionProcess(int process_id);
 
   // NotificationObserver:
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
                        const NotificationDetails& details);
 
   typedef std::set<ExtensionHost*> ExtensionHostSet;
@@ skipping 18 matching lines @@
   scoped_refptr<BrowsingInstance> browsing_instance_;
 
   // A map of extension ID to the render_process_id that the extension lives in.
   typedef std::map<std::string, int> ProcessIDMap;
   ProcessIDMap process_ids_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionProcessManager);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_PROCESS_MANAGER_H_