Fix Arc integration test.

chrome/browser/sync/test/integration/single_client_arc_package_sync_test.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/profiles/profile.h"
 #include "chrome/browser/sync/test/integration/sync_arc_package_helper.h"
 #include "chrome/browser/sync/test/integration/sync_test.h"
 #include "chrome/browser/sync/test/integration/updated_progress_marker_checker.h"
+#include "chrome/browser/ui/app_list/arc/arc_app_list_prefs_factory.h"
 #include "chrome/browser/ui/app_list/arc/arc_package_syncable_service.h"
 
 namespace arc {
 
 namespace {
 
 bool AllProfilesHaveSameArcPackageDetails() {
   return SyncArcPackageHelper::GetInstance()
       ->AllProfilesHaveSamePackageDetails();
 }
@@ skipping 10 matching lines @@
   bool SetupClients() override {
     if (!SyncTest::SetupClients())
       return false;
 
     // Init SyncArcPackageHelper to ensure that the arc services are initialized
     // for each Profile.
     sync_helper_ = SyncArcPackageHelper::GetInstance();
     return sync_helper_ != nullptr;
   }
 
+  void SetUpOnMainThread() override {

[lgcheng, 2017/02/22 23:36:44]

Moved from sync_arc_package_helper. It seems the execution order of
SetFactoryForSyncTest() and setupService() is not guaranteed by compiler due to
the complexity of construction of ArcAppListPrefs. 

+    ArcAppListPrefsFactory::SetFactoryForSyncTest();
+  }
+
   void TearDownOnMainThread() override {
     sync_helper_->CleanUp();
     sync_helper_ = nullptr;
     SyncTest::TearDownOnMainThread();
   }
 
   SyncArcPackageHelper* sync_helper() { return sync_helper_; }
 
  private:
   SyncArcPackageHelper* sync_helper_;
@@ skipping 15 matching lines @@
   for (size_t i = 0; i < kNumPackages; ++i) {
     sync_helper()->InstallPackageWithIndex(GetProfile(0), i);
     sync_helper()->InstallPackageWithIndex(verifier(), i);
   }
 
   ASSERT_TRUE(UpdatedProgressMarkerChecker(GetSyncService(0)).Wait());
   ASSERT_TRUE(AllProfilesHaveSameArcPackageDetails());
 }
 
 }  // namespace arc