Add a SetCanonicalCookie method for CookieMonster.

net/cookies/cookie_store_test_helpers.h

Index: net/cookies/cookie_store_test_helpers.h
diff --git a/net/cookies/cookie_store_test_helpers.h b/net/cookies/cookie_store_test_helpers.h
index bb6d656b140c3fd91b42c631d2382ffef467ba78..9170ea5cee7cb34c29d39197354dbfd3432e7937 100644
--- a/net/cookies/cookie_store_test_helpers.h
+++ b/net/cookies/cookie_store_test_helpers.h
@@ -45,6 +45,11 @@ class DelayedCookieMonster : public CookieStore {
                                  CookiePriority priority,
                                  const SetCookiesCallback& callback) override;
 
+  void SetCanonicalCookieAsync(const CanonicalCookie& cookie,
+                               bool secure_source,
+                               bool modify_http_only,
+                               const SetCookiesCallback& callback) override;
+
   void GetCookiesWithOptionsAsync(
       const GURL& url,
       const CookieOptions& options,