Revert "Sync: Avoid deadlock in SyncBackendRegistrar / ModelSafeWorker on sync backend shutdown."

chrome/browser/sync/glue/sync_backend_registrar_unittest.cc

Index: chrome/browser/sync/glue/sync_backend_registrar_unittest.cc
diff --git a/chrome/browser/sync/glue/sync_backend_registrar_unittest.cc b/chrome/browser/sync/glue/sync_backend_registrar_unittest.cc
index f1a62ee0ff836c71d597881825cbb49745ec80f9..cd2d29ddf4edfdb88cc9ecefb6feab6cab9e8586 100644
--- a/chrome/browser/sync/glue/sync_backend_registrar_unittest.cc
+++ b/chrome/browser/sync/glue/sync_backend_registrar_unittest.cc
@@ -256,91 +256,6 @@ TEST_F(SyncBackendRegistrarTest, ActivateDeactivateNonUIDataType) {
   TriggerChanges(registrar_.get(), AUTOFILL);
 }
 
-class SyncBackendRegistrarShutdownTest : public testing::Test {
- public:
-  void BlockDBThread() {
-    EXPECT_FALSE(db_thread_lock_.Try());
-
-    db_thread_blocked_.Signal();
-    base::AutoLock l(db_thread_lock_);
-  }
-
- protected:
-  friend class TestRegistrar;
-
-  SyncBackendRegistrarShutdownTest()
-      : thread_bundle_(content::TestBrowserThreadBundle::REAL_DB_THREAD |
-                       content::TestBrowserThreadBundle::REAL_FILE_THREAD |
-                       content::TestBrowserThreadBundle::REAL_IO_THREAD),
-        db_thread_blocked_(false, false),
-        registrar_destroyed_(false, false) {}
-
-  virtual ~SyncBackendRegistrarShutdownTest() {}
-
-  content::TestBrowserThreadBundle thread_bundle_;
-  base::WaitableEvent db_thread_blocked_;
-  base::Lock db_thread_lock_;
-  base::WaitableEvent registrar_destroyed_;
-};
-
-// Wrap SyncBackendRegistrar so that we can monitor its lifetime.
-class TestRegistrar : public SyncBackendRegistrar {
- public:
-  explicit TestRegistrar(Profile* profile,
-                         SyncBackendRegistrarShutdownTest* test)
-      : SyncBackendRegistrar("test", profile, scoped_ptr<base::Thread>()),
-        test_(test) {}
-
-  ~TestRegistrar() override { test_->registrar_destroyed_.Signal(); }
-
- private:
-  SyncBackendRegistrarShutdownTest* test_;
-};
-
-TEST_F(SyncBackendRegistrarShutdownTest, BlockingShutdown) {
-  // Take ownership of |db_thread_lock_| so that the DB thread can't acquire it.
-  db_thread_lock_.Acquire();
-
-  // This will block the DB thread by waiting on |db_thread_lock_|.
-  BrowserThread::PostTask(
-      BrowserThread::DB,
-      FROM_HERE,
-      base::Bind(&SyncBackendRegistrarShutdownTest::BlockDBThread,
-                 base::Unretained(this)));
-
-  TestingProfile profile;
-  scoped_ptr<TestRegistrar> registrar(new TestRegistrar(&profile, this));
-  base::Thread* sync_thread = registrar->sync_thread();
-
-  // Stop here until the DB thread gets a chance to run and block on the lock.
-  // Please note that since the task above didn't finish, the task to
-  // initialize the worker on the DB thread hasn't had a chance to run yet too.
-  // Which means ModelSafeWorker::SetWorkingLoopToCurrent hasn't been called
-  // for the DB worker.
-  db_thread_blocked_.Wait();
-
-  registrar->SetInitialTypes(ModelTypeSet());
-
-  // Start the shutdown.
-  registrar->RequestWorkerStopOnUIThread();
-  sync_thread->message_loop()->PostTask(
-      FROM_HERE,
-      base::Bind(&SyncBackendRegistrar::Shutdown,
-                 base::Unretained(registrar.release())));
-
-  // The test verifies that the sync thread doesn't block because
-  // of the blocked DB thread and can finish the shutdown.
-  sync_thread->message_loop()->RunUntilIdle();
-
-  db_thread_lock_.Release();
-
-  base::MessageLoop::current()->RunUntilIdle();
-
-  // This verifies that all workers have been removed and the registrar
-  // destroyed.
-  registrar_destroyed_.Wait();
-}
-
 }  // namespace
 
 }  // namespace browser_sync