[SyncFS] Add exclusive task support for TaskDependencyManager

chrome/browser/sync_file_system/drive_backend/task_dependency_manager_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/task_dependency_manager.h"
 
 #include "base/files/file_path.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 #define FPL(path) FILE_PATH_LITERAL(path)
@@ skipping 18 matching lines @@
 
 void ErasePath(TaskDependencyManager* manager,
                const std::string& app_id,
                const base::FilePath::StringType& path) {
   BlockingFactor blocker;
   blocker.app_id = app_id;
   blocker.paths.push_back(MakePath(path));
   return manager->Erase(blocker);
 }
 
+bool InsertExclusiveTask(TaskDependencyManager* manager) {
+  BlockingFactor blocker;
+  blocker.exclusive = true;
+  return manager->Insert(blocker);
+}
+
+void EraseExclusiveTask(TaskDependencyManager* manager) {
+  BlockingFactor blocker;
+  blocker.exclusive = true;
+  manager->Erase(blocker);
+}
+
 }  // namespace
 
 TEST(TaskDependencyManagerTest, BasicTest) {
   TaskDependencyManager manager;
   BlockingFactor blocker;
   blocker.app_id = "app_id";
   blocker.paths.push_back(MakePath(FPL("/folder/file")));
   blocker.file_ids.push_back("file_id");
   blocker.tracker_ids.push_back(100);
 
@@ skipping 23 matching lines @@
   EXPECT_TRUE(InsertPath(
       &manager, "another_app_id", FPL("/ancestor/parent/self")));
   ErasePath(&manager, "another_app_id", FPL("/ancestor/parent/self"));
 
   EXPECT_TRUE(InsertPath(&manager, "app_id", FPL("/file")));
   ErasePath(&manager, "app_id", FPL("/file"));
 
   ErasePath(&manager, "app_id", FPL("/ancestor/parent/self/child/descendant"));
 }
 
+TEST(TaskDependencyManagerTest, ExclusiveTask) {
+  TaskDependencyManager manager;
+
+  EXPECT_TRUE(InsertPath(&manager, "app_id", FPL("/foo/bar")));
+  EXPECT_FALSE(InsertExclusiveTask(&manager));
+  ErasePath(&manager, "app_id", FPL("/foo/bar"));
+
+  EXPECT_TRUE(InsertExclusiveTask(&manager));
+  EXPECT_FALSE(InsertPath(&manager, "app_id", FPL("/foo/bar")));
+  EraseExclusiveTask(&manager);
+
+  EXPECT_TRUE(InsertPath(&manager, "app_id", FPL("/foo/bar")));
+  ErasePath(&manager, "app_id", FPL("/foo/bar"));
+}
+
 }  // namespace drive_backend
 }  // namespace sync_file_system