Adds a first integration test for the Recent Tabs feature.

components/offline_pages/core/offline_page_feature.cc

 // Copyright 2015 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/core/offline_page_feature.h"
 
 #include <string>
 
+#include "base/command_line.h"
 #include "base/feature_list.h"
 
+namespace switches {
+
+// This flag significantly shortens the delay between WebContentsObserver events
+// and SnapshotController's StartSnapshot calls. The purpose is to speed up
+// integration tests.
+const char kOfflinePagesUseTestingSnapshotDelay[] =
+    "short-offline-page-snapshot-delay-for-test";
+
+}  // namespace switches
+
 namespace offline_pages {
 
 const base::Feature kOfflineBookmarksFeature{"OfflineBookmarks",
                                              base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kOffliningRecentPagesFeature{
     "OfflineRecentPages", base::FEATURE_DISABLED_BY_DEFAULT};
 
 const base::Feature kOfflinePagesCTFeature{"OfflinePagesCT",
                                            base::FEATURE_ENABLED_BY_DEFAULT};
@@ skipping 40 matching lines @@
 }
 
 bool IsOfflinePagesAsyncDownloadEnabled() {
   return base::FeatureList::IsEnabled(kOfflinePagesAsyncDownloadFeature);
 }
 
 bool ShouldUseNewBackgroundLoader() {
   return base::FeatureList::IsEnabled(kNewBackgroundLoaderFeature);
 }
 
+bool ShouldUseTestingSnapshotDelay() {
+  base::CommandLine* cl = base::CommandLine::ForCurrentProcess();
+  return cl->HasSwitch(switches::kOfflinePagesUseTestingSnapshotDelay);
+}
+
 }  // namespace offline_pages