drive: Implement lock mechanism to ChangeListLoader

chrome/browser/chromeos/drive/change_list_loader_unittest.cc

 // Copyright 2013 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/chromeos/drive/change_list_loader.h"
 
+#include "base/callback_helpers.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/prefs/testing_pref_service.h"
 #include "base/run_loop.h"
 #include "chrome/browser/chromeos/drive/change_list_loader_observer.h"
 #include "chrome/browser/chromeos/drive/file_cache.h"
 #include "chrome/browser/chromeos/drive/file_system_util.h"
 #include "chrome/browser/chromeos/drive/job_scheduler.h"
 #include "chrome/browser/chromeos/drive/resource_metadata.h"
 #include "chrome/browser/chromeos/drive/test_util.h"
@@ skipping 403 matching lines @@
       util::GetDriveMyDriveRootPath()));
 
   // The new file is found in the local metadata.
   base::FilePath new_file_path =
       util::GetDriveMyDriveRootPath().AppendASCII(gdata_entry->title());
   ResourceEntry entry;
   EXPECT_EQ(FILE_ERROR_OK,
             metadata_->GetResourceEntryByPath(new_file_path, &entry));
 }
 
+TEST_F(ChangeListLoaderTest, Lock) {
+  FileError error = FILE_ERROR_FAILED;
+  change_list_loader_->LoadForTesting(
+      google_apis::test_util::CreateCopyResultCallback(&error));
+  base::RunLoop().RunUntilIdle();
+  EXPECT_EQ(FILE_ERROR_OK, error);
+
+  // Add a new file.
+  scoped_ptr<google_apis::ResourceEntry> file = AddNewFile("New File");
+  ASSERT_TRUE(file);
+
+  // Lock the loader.
+  scoped_ptr<base::ScopedClosureRunner> lock = change_list_loader_->GetLock();
+
+  // Start update.
+  TestChangeListLoaderObserver observer(change_list_loader_.get());
+  FileError check_for_updates_error = FILE_ERROR_FAILED;
+  change_list_loader_->CheckForUpdates(
+      google_apis::test_util::CreateCopyResultCallback(
+          &check_for_updates_error));
+  base::RunLoop().RunUntilIdle();
+
+  // Update is pending due to the lock.
+  EXPECT_TRUE(observer.changed_directories().empty());
+
+  // Unlock the loader, this should resume the pending udpate.
+  lock.reset();
+  base::RunLoop().RunUntilIdle();
+  EXPECT_EQ(1U, observer.changed_directories().count(
+      util::GetDriveMyDriveRootPath()));
+}
+
 }  // namespace internal
 }  // namespace drive