Add AddCallbackForCookie method to CookieStore.

net/cookies/cookie_store_test_helpers.cc

Index: net/cookies/cookie_store_test_helpers.cc
diff --git a/net/cookies/cookie_store_test_helpers.cc b/net/cookies/cookie_store_test_helpers.cc
index fdf2c1f1ee803432f21ce74977ee6cb7869209ea..bcf8c897c709da2fc9b6c4f0394c069f86a5870b 100644
--- a/net/cookies/cookie_store_test_helpers.cc
+++ b/net/cookies/cookie_store_test_helpers.cc
@@ -135,4 +135,13 @@ CookieMonster* DelayedCookieMonster::GetCookieMonster() {
   return cookie_monster_.get();
 }
 
+scoped_ptr<CookieStore::CookieChangedSubscription>
+DelayedCookieMonster::AddCallbackForCookie(
+    const GURL& url,
+    const std::string& name,
+    const CookieChangedCallback& callback) {
+  ADD_FAILURE();
+  return scoped_ptr<CookieStore::CookieChangedSubscription>();
+}
+
 }  // namespace net