[SyncFS] Add exclusive task support for TaskDependencyManager

chrome/browser/sync_file_system/drive_backend/task_dependency_manager_unittest.cc

Index: chrome/browser/sync_file_system/drive_backend/task_dependency_manager_unittest.cc
diff --git a/chrome/browser/sync_file_system/drive_backend/task_dependency_manager_unittest.cc b/chrome/browser/sync_file_system/drive_backend/task_dependency_manager_unittest.cc
index 6fe5317c10f019813c126165570893154691a690..488793258f59b37725838e1eb2ac66d697fac64e 100644
--- a/chrome/browser/sync_file_system/drive_backend/task_dependency_manager_unittest.cc
+++ b/chrome/browser/sync_file_system/drive_backend/task_dependency_manager_unittest.cc
@@ -36,6 +36,18 @@ void ErasePath(TaskDependencyManager* manager,
   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) {
@@ -79,5 +91,20 @@ TEST(TaskDependencyManagerTest, BlocksAncestorAndDescendant) {
   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