Add AddCallbackForCookie method to CookieStore.

net/websockets/websocket_job_test.cc

Index: net/websockets/websocket_job_test.cc
diff --git a/net/websockets/websocket_job_test.cc b/net/websockets/websocket_job_test.cc
index 3faf8093f3719568e28b9b037f2a68c9c2e729a4..f78a08132172257d2d9813396c4faa536b2b1e52 100644
--- a/net/websockets/websocket_job_test.cc
+++ b/net/websockets/websocket_job_test.cc
@@ -228,6 +228,13 @@ class MockCookieStore : public CookieStore {
 
   CookieMonster* GetCookieMonster() override { return NULL; }
 
+  scoped_ptr<CookieStore::CookieChangedSubscription>
+  AddCallbackForCookie(const GURL& url, const std::string& name,
+                       const CookieChangedCallback& callback) override {
+    ADD_FAILURE();
+    return scoped_ptr<CookieChangedSubscription>();
+  }
+
   const std::vector<Entry>& entries() const { return entries_; }
 
  private: