[SyncFS] Introduce CallbackTracker to handle callback abortion

chrome/browser/sync_file_system/drive_backend/callback_tracker_unittest.cc

+// Copyright 2014 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/sync_file_system/drive_backend/callback_tracker.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace sync_file_system {
+namespace drive_backend {
+
+namespace {
+
+void Receiver(bool* called) {
+  DCHECK(called);
+  EXPECT_FALSE(*called);
+  *called = true;
+}
+
+}  // namespace
+
+TEST(CallbackTrackerTest, AbortAll) {
+  CallbackTracker tracker;
+
+  bool aborted = false;
+  bool invoked = false;
+  base::Closure callback = tracker.Register(base::Bind(&Receiver, &aborted),
+                                            base::Bind(&Receiver, &invoked));
+  tracker.AbortAll();
+  EXPECT_TRUE(aborted);
+  EXPECT_FALSE(invoked);
+
+  callback.Run();
+  EXPECT_TRUE(aborted);
+  EXPECT_FALSE(invoked);
+}
+
+TEST(CallbackTrackerTest, Invoke) {
+  CallbackTracker tracker;
+
+  bool aborted = false;
+  bool invoked = false;
+  base::Closure callback = tracker.Register(base::Bind(&Receiver, &aborted),
+                                            base::Bind(&Receiver, &invoked));
+  callback.Run();
+  EXPECT_FALSE(aborted);
+  EXPECT_TRUE(invoked);
+
+  // Second call should not do anything.
+  invoked = false;
+  callback.Run();
+  EXPECT_FALSE(invoked);
+
+  tracker.AbortAll();
+  EXPECT_FALSE(aborted);
+}
+
+}  // namespace drive_backend
+}  // namespace sync_file_system