[Offline Pages] Add a timer to BackgroundLoaderOffliner to delay SavePage by 2 seconds.

chrome/browser/android/offline_pages/background_loader_offliner_unittest.cc

 // Copyright 2016 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/android/offline_pages/background_loader_offliner.h"
 
 #include "base/bind.h"
 #include "base/run_loop.h"
 #include "base/test/histogram_tester.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 350 matching lines @@
   offliner()->DidFinishNavigation(handle.get());
   // NavigationHandle is always destroyed after finishing navigation.
   handle.reset();
   offliner()->DidStopLoading();
   PumpLoop();
 
   EXPECT_TRUE(completion_callback_called());
   EXPECT_EQ(Offliner::RequestStatus::LOADING_FAILED_NO_RETRY, request_status());
 }
 
+TEST_F(BackgroundLoaderOfflinerTest, OnlySavesOnceOnMultipleLoads) {
+  base::Time creation_time = base::Time::Now();
+  SavePageRequest request(kRequestId, kHttpUrl, kClientId, creation_time,
+                          kUserRequested);
+  EXPECT_TRUE(offliner()->LoadAndSave(request, callback()));
+  // First load
+  CompleteLoading();
+  // Second load
+  offliner()->DidStopLoading();
+  PumpLoop();
+  model()->CompleteSavingAsSuccess();
+  PumpLoop();
+
+  EXPECT_TRUE(completion_callback_called());
+  EXPECT_EQ(Offliner::RequestStatus::SAVED, request_status());
+  EXPECT_FALSE(offliner()->is_loading());
+  EXPECT_FALSE(SaveInProgress());
+}
+
 }  // namespace offline_pages