Remove unnecessary image downloading handler of notifications.

chrome/browser/notifications/extension_welcome_notification_unittest.cc

 // Copyright 2014 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.
 
 #include "chrome/browser/notifications/extension_welcome_notification.h"
 
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 199 matching lines @@
 
     // Overridden from NotificationDelegate:
     virtual void Display() override {}
     virtual void Error() override {}
     virtual void Close(bool by_user) override {}
     virtual void Click() override {}
     virtual void ButtonClick(int index) override {}
 
     virtual std::string id() const override { return id_; }
 
-    virtual content::WebContents* GetWebContents() const override {
-      return NULL;
-    }
-
    private:
     virtual ~TestNotificationDelegate() {}
 
     const std::string id_;
 
     DISALLOW_COPY_AND_ASSIGN(TestNotificationDelegate);
   };
 
   void ShowNotification(std::string notification_id,
                         const message_center::NotifierId& notifier_id) const {
@@ skipping 307 matching lines @@
 
   EXPECT_TRUE(task_runner()->GetPendingTasks().empty());
   EXPECT_EQ(message_center()->add_notification_calls(), 0);
   EXPECT_EQ(message_center()->remove_notification_calls(), 0);
   EXPECT_EQ(message_center()->notifications_with_shown_as_popup(), 0);
   EXPECT_FALSE(GetBooleanPref(prefs::kWelcomeNotificationDismissed));
   EXPECT_TRUE(GetBooleanPref(prefs::kWelcomeNotificationDismissedLocal));
   EXPECT_TRUE(GetBooleanPref(prefs::kWelcomeNotificationPreviouslyPoppedUp));
   EXPECT_EQ(GetInt64Pref(prefs::kWelcomeNotificationExpirationTimestamp), 1);
 }