[Media Router] Fix unit test "DeviceDescriptionServiceTest.TestCleanUpCacheEntries"

chrome/browser/media/router/discovery/dial/device_description_service_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 "chrome/browser/media/router/discovery/dial/device_description_service.h"
 
 #include "base/strings/stringprintf.h"
 #include "base/test/mock_callback.h"
 #include "chrome/browser/media/router/discovery/dial/device_description_fetcher.h"
 #include "chrome/browser/media/router/discovery/dial/dial_device_data.h"
@@ skipping 82 matching lines @@
         thread_bundle_(content::TestBrowserThreadBundle::IO_MAINLOOP) {}
 
   TestDeviceDescriptionService* device_description_service() {
     return &device_description_service_;
   }
 
   void AddToCache(const std::string& device_label,
                   const ParsedDialDeviceDescription& description_data,
                   bool expired) {
     DeviceDescriptionService::CacheEntry cache_entry;
-    cache_entry.expire_time = base::Time::Now();
-    if (!expired)
-      cache_entry.expire_time += base::TimeDelta::FromHours(12);
+    cache_entry.expire_time =
+        base::Time::Now() + (expired ? -1 : 1) * base::TimeDelta::FromHours(12);
     cache_entry.description_data = description_data;
     description_cache_[device_label] = cache_entry;
   }
 
   void SetTestParser(
       std::unique_ptr<TestSafeDialDeviceDescriptionParser> test_parser) {
     if (device_description_service_.parser_)
       return;
     device_description_service_.parser_ = std::move(test_parser);
   }
@@ skipping 124 matching lines @@
 
   EXPECT_CALL(mock_error_cb_, Run(_, _)).Times(3);
   device_description_service()->OnDeviceDescriptionFetchError(device_data_1,
                                                               "");
   device_description_service()->OnDeviceDescriptionFetchError(device_data_2,
                                                               "");
   device_description_service()->OnDeviceDescriptionFetchError(device_data_3,
                                                               "");
 }
 
-// Flaky: https://crbug.com/716810
-TEST_F(DeviceDescriptionServiceTest, DISABLED_TestCleanUpCacheEntries) {
+TEST_F(DeviceDescriptionServiceTest, TestCleanUpCacheEntries) {
   DialDeviceData device_data_1 = CreateDialDeviceData(1);
   DialDeviceData device_data_2 = CreateDialDeviceData(2);
   DialDeviceData device_data_3 = CreateDialDeviceData(3);
 
   AddToCache(device_data_1.label(), ParsedDialDeviceDescription(),
              true /* expired */);
   AddToCache(device_data_2.label(), ParsedDialDeviceDescription(),
              true /* expired */);
   AddToCache(device_data_3.label(), ParsedDialDeviceDescription(),
              false /* expired */);
@@ skipping 58 matching lines @@
   OnDeviceDescriptionFetchComplete(1);
 
   EXPECT_TRUE(device_description_service()->parser_);
   OnDeviceDescriptionFetchComplete(2);
   OnDeviceDescriptionFetchComplete(3);
 
   EXPECT_FALSE(device_description_service()->parser_);
 }
 
 }  // namespace media_router