[Offline Pages] Add a GCMAppHandler for offline page prefetch.

components/offline_pages/content/suggested_articles_observer_unittest.cc

 // Copyright 2017 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 "components/offline_pages/content/suggested_articles_observer.h"
 
 #include "base/run_loop.h"
 #include "base/test/test_simple_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/offline_pages/core/client_namespace_constants.h"
 #include "components/offline_pages/core/stub_offline_page_model.h"
 #include "content/public/test/test_browser_context.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "url/gurl.h"
 
 using ntp_snippets::Category;
 using ntp_snippets::ContentSuggestion;
 
+namespace gcm {
+class GCMDriver;
+}
+
 namespace offline_pages {
 
 namespace {
 
 ContentSuggestion ContentSuggestionFromTestURL(const GURL& test_url) {
   auto category =
       Category::FromKnownCategory(ntp_snippets::KnownCategories::ARTICLES);
   return ContentSuggestion(category, test_url.spec(), test_url);
 }
 
@@ skipping 16 matching lines @@
 
   void RemovePrefetchURLsByClientId(const ClientId& client_id) override {
     DCHECK_EQ(client_id.name_space, kSuggestedArticlesNamespace);
     remove_by_client_id_count++;
     last_removed_client_id = base::MakeUnique<ClientId>(client_id);
   }
 
   void BeginBackgroundTask(
       std::unique_ptr<ScopedBackgroundTask> task) override {}
   void StopBackgroundTask(ScopedBackgroundTask* task) override {}
+  void RegisterWithGCMDriver(gcm::GCMDriver* driver) override {}
 
   std::vector<PrefetchURL> latest_prefetch_urls;
   std::unique_ptr<ClientId> last_removed_client_id;
 
   int new_suggestions_count = 0;
   int remove_all_suggestions_count = 0;
   int remove_by_client_id_count = 0;
 };
 
 class TestDelegate : public SuggestedArticlesObserver::Delegate {
@@ skipping 124 matching lines @@
 
   observer()->OnSuggestionInvalidated(
       ntp_snippets::ContentSuggestion::ID(category, test_url_1.spec()));
 
   EXPECT_EQ(1, test_prefetch_service()->remove_by_client_id_count);
   EXPECT_EQ(ClientId(kSuggestedArticlesNamespace, test_url_1.spec()),
             *test_prefetch_service()->last_removed_client_id);
 }
 
 }  // namespace offline_pages