PrerenderingOffliner will abort background load if it sees chrome transitioning to foreground on lo…

chrome/browser/android/offline_pages/prerendering_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/prerendering_offliner.h"
 
 #include <memory>
 
 #include "base/bind.h"
 #include "base/run_loop.h"
+#include "base/sys_info.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "chrome/browser/android/offline_pages/prerendering_loader.h"
 #include "chrome/test/base/testing_profile.h"
 #include "components/offline_pages/background/offliner.h"
 #include "components/offline_pages/background/save_page_request.h"
 #include "components/offline_pages/stub_offline_page_model.h"
 #include "content/public/test/test_browser_thread_bundle.h"
 #include "content/public/test/web_contents_tester.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ skipping 300 matching lines @@
 
   loader()->CompleteLoadingAsCanceled();
   PumpLoop();
   EXPECT_TRUE(completion_callback_called());
   EXPECT_EQ(Offliner::RequestStatus::PRERENDERING_CANCELED, request_status());
   EXPECT_FALSE(loader()->IsLoaded());
   // Note: save still in progress since it does not support canceling.
   EXPECT_TRUE(SaveInProgress());
 }
 
+TEST_F(PrerenderingOfflinerTest, CancelOnForegroundTransitionIfLowEndDevice) {
+  base::Time creation_time = base::Time::Now();
+  SavePageRequest request(kRequestId, kHttpUrl, kClientId, creation_time);
+  EXPECT_TRUE(offliner()->LoadAndSave(request, callback()));
+  EXPECT_FALSE(loader()->IsIdle());
+
+  offliner()->SetApplicationStateForTesting(
+      base::android::APPLICATION_STATE_HAS_RUNNING_ACTIVITIES);
+
+  if (base::SysInfo::IsLowEndDevice()) {

[Pete Williamson, 2016/07/13 23:17:55]

This seems a bit problematic, the build bots may be either all or no low end
devices.

Instead, is there a way to get base::SysInfo::IsLowEndDevice to return true for
your test?

Did you test this on both kinds of devices, and verify both paths passed?

[dougarnett, 2016/07/13 23:44:20]

I tried to address this point in advance in original mail message for this CL so
I will paste here to see if it answers or was unclear: 

Fyi, I verified this change manually on low-end device. I wasn't able to run the
unit tests on that device though so actually exercising new unit test on low-end
device should get picked up by Lollipop Low-end Tester after submission.

[Pete Williamson, 2016/07/13 23:57:12]

I'd really like to see this tested on both before submission.  I have a low end
device you may borrow.

I'd also like to know if it is possible to mock out the
base::SysInfo::IsLowEndDevice() call to return true for our unit test.

[dougarnett, 2016/07/14 15:29:21]

Acknowledged - I will look to mock the case.

Please try to run a unit test on your low-end device and see if it will run it.
It would be sweet if we have one that will.

[dougarnett, 2016/07/15 16:00:25]

Done.

[Pete Williamson, 2016/07/16 00:57:20]

I don't see the change to mock, is it uploaded yet?  In a different file?
Also, once we have the change, we can get rid of the if statement, since we will
always be testing on a (simulated) low end device.

+    EXPECT_TRUE(loader()->IsIdle());
+    EXPECT_EQ(Offliner::RequestStatus::FOREGROUND_CANCELED, request_status());
+  } else {
+    // Loader still loading if not low-end device.
+    EXPECT_FALSE(loader()->IsIdle());
+  }
+}
+
 }  // namespace offline_pages