Change event routers from singletons to being owned by the ExtensionService.

chrome/browser/extensions/extension_cookies_api.h

Index: chrome/browser/extensions/extension_cookies_api.h
diff --git a/chrome/browser/extensions/extension_cookies_api.h b/chrome/browser/extensions/extension_cookies_api.h
index 286c8badb014dddf0435f4f610c877f9672e9aa6..276c336a8b3c93242d794c8b9b6b36a13d504d55 100644
--- a/chrome/browser/extensions/extension_cookies_api.h
+++ b/chrome/browser/extensions/extension_cookies_api.h
@@ -12,7 +12,6 @@
 #include <string>
 
 #include "base/memory/ref_counted.h"
-#include "base/memory/singleton.h"
 #include "base/time.h"
 #include "chrome/browser/extensions/extension_function.h"
 #include "chrome/browser/net/chrome_cookie_notification_details.h"
@@ -31,17 +30,12 @@ class URLRequestContextGetter;
 // extension system.
 class ExtensionCookiesEventRouter : public NotificationObserver {
  public:
-  // Single instance of the event router.
-  static ExtensionCookiesEventRouter* GetInstance();
+  explicit ExtensionCookiesEventRouter();
+  virtual ~ExtensionCookiesEventRouter();
 
   void Init();
 
  private:
-  friend struct DefaultSingletonTraits<ExtensionCookiesEventRouter>;
-
-  ExtensionCookiesEventRouter() {}
-  virtual ~ExtensionCookiesEventRouter() {}
-
   // NotificationObserver implementation.
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,