1 // Copyright 2016 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include <memory> 6 #include <utility> 7 8 #include "base/macros.h" 9 #include "base/run_loop.h" 10 #include "base/task/cancelable_task_tracker.h" 11 #include "chrome/browser/history/history_service_factory.h" 12 #include "components/history/core/browser/history_db_task.h" 13 #include "components/history/core/browser/history_service.h" 14 #include "content/public/test/test_utils.h" 15 16 namespace { 17 18 // Note: WaitableEvent is not used for synchronization between the main thread 19 // and history backend thread because the history subsystem posts tasks back 20 // to the main thread. Had we tried to Signal an event in such a task 21 // and Wait for it on the main thread, the task would not run at all because 22 // the main thread would be blocked on the Wait call, resulting in a deadlock. 23 24 // A task to be scheduled on the history backend thread. 25 // Notifies the main thread after all history backend thread tasks have run. 26 class WaitForHistoryTask : public history::HistoryDBTask { 27 public: WaitForHistoryTask()28 WaitForHistoryTask() {} 29 RunOnDBThread(history::HistoryBackend * backend,history::HistoryDatabase * db)30 bool RunOnDBThread(history::HistoryBackend* backend, 31 history::HistoryDatabase* db) override { 32 return true; 33 } 34 DoneRunOnMainThread()35 void DoneRunOnMainThread() override { 36 base::RunLoop::QuitCurrentWhenIdleDeprecated(); 37 } 38 39 private: ~WaitForHistoryTask()40 ~WaitForHistoryTask() override {} 41 42 DISALLOW_COPY_AND_ASSIGN(WaitForHistoryTask); 43 }; 44 45 } // namespace 46 WaitForHistoryBackendToRun(Profile * profile)47void WaitForHistoryBackendToRun(Profile* profile) { 48 base::CancelableTaskTracker task_tracker; 49 std::unique_ptr<history::HistoryDBTask> task(new WaitForHistoryTask()); 50 history::HistoryService* history = HistoryServiceFactory::GetForProfile( 51 profile, ServiceAccessType::EXPLICIT_ACCESS); 52 history->ScheduleDBTask(FROM_HERE, std::move(task), &task_tracker); 53 content::RunMessageLoop(); 54 } 55