scheduler: Implement task observers

content/renderer/scheduler/task_queue_manager_unittest.cc

Index: content/renderer/scheduler/task_queue_manager_unittest.cc
diff --git a/content/renderer/scheduler/task_queue_manager_unittest.cc b/content/renderer/scheduler/task_queue_manager_unittest.cc
index 62e6c349c372dd16a92bd74488a27f23eaf3743a..85d428ee9b2c42e8c6045b4987de23c57b680373 100644
--- a/content/renderer/scheduler/task_queue_manager_unittest.cc
+++ b/content/renderer/scheduler/task_queue_manager_unittest.cc
@@ -11,6 +11,7 @@
 #include "testing/gmock/include/gmock/gmock.h"
 
 using testing::ElementsAre;
+using testing::_;
 
 namespace content {
 namespace {
@@ -582,5 +583,87 @@ TEST_F(TaskQueueManagerTest, InterruptWorkBatchForDelayedTask) {
   EXPECT_THAT(run_order, ElementsAre(2, 3, 1));
 }
 
+class MockTaskObserver : public base::MessageLoop::TaskObserver {
+ public:
+  MOCK_METHOD1(DidProcessTask, void(const base::PendingTask& task));
+  MOCK_METHOD1(WillProcessTask, void(const base::PendingTask& task));
+};
+
+TEST_F(TaskQueueManagerTest, TaskObserverAdding) {
+  Initialize(1u);
+  MockTaskObserver observer;
+
+  manager_->SetWorkBatchSize(2);
+  manager_->AddTaskObserver(&observer);
+
+  std::vector<int> run_order;
+  scoped_refptr<base::SingleThreadTaskRunner> runner =
+      manager_->TaskRunnerForQueue(0);
+
+  runner->PostTask(FROM_HERE, base::Bind(&TestTask, 1, &run_order));
+  runner->PostTask(FROM_HERE, base::Bind(&TestTask, 2, &run_order));
+
+  selector_->AppendQueueToService(0);
+  selector_->AppendQueueToService(0);
+
+  // The observer should be called once because the first and last
+  // notifications are filtered out.

[rmcilroy, 2015/02/23 22:41:43]

These test results now look a bit strange - looking at them I think it might
confuse people that to get all task observer messages they need to register a
task observer on both the TQM and the underlying message loop.  Could we have
the TQM register the task observer on the underlying message loop as well, thus
allowing observation of all tasks just by registering on the TQM?

[Sami, 2015/02/24 14:39:20]

Yeah, I suppose that would be clearer because generally you want both types of
notifications. Done.

+  EXPECT_CALL(observer, WillProcessTask(_)).Times(1);
+  EXPECT_CALL(observer, DidProcessTask(_)).Times(1);
+  test_task_runner_->RunUntilIdle();
+}
+
+TEST_F(TaskQueueManagerTest, TaskObserverRemoving) {
+  Initialize(1u);
+  MockTaskObserver observer;
+  manager_->SetWorkBatchSize(2);
+  manager_->AddTaskObserver(&observer);
+  manager_->RemoveTaskObserver(&observer);
+
+  std::vector<int> run_order;
+  scoped_refptr<base::SingleThreadTaskRunner> runner =
+      manager_->TaskRunnerForQueue(0);
+
+  runner->PostTask(FROM_HERE, base::Bind(&TestTask, 1, &run_order));
+
+  EXPECT_CALL(observer, WillProcessTask(_)).Times(0);
+  EXPECT_CALL(observer, DidProcessTask(_)).Times(0);
+
+  selector_->AppendQueueToService(0);
+  test_task_runner_->RunUntilIdle();
+}
+
+void RemoveObserverTask(TaskQueueManager* manager,
+                        base::MessageLoop::TaskObserver* observer) {
+  manager->RemoveTaskObserver(observer);
+}
+
+void NoOpTask() {
+}
+
+TEST_F(TaskQueueManagerTest, TaskObserverRemovingInsideTask) {
+  Initialize(1u);
+  MockTaskObserver observer;
+  manager_->SetWorkBatchSize(3);
+  manager_->AddTaskObserver(&observer);
+
+  scoped_refptr<base::SingleThreadTaskRunner> runner =
+      manager_->TaskRunnerForQueue(0);
+  runner->PostTask(FROM_HERE, base::Bind(&NoOpTask));
+  runner->PostTask(FROM_HERE,
+                   base::Bind(&RemoveObserverTask, manager_.get(), &observer));
+  runner->PostTask(FROM_HERE, base::Bind(&NoOpTask));
+
+  selector_->AppendQueueToService(0);
+  selector_->AppendQueueToService(0);
+  selector_->AppendQueueToService(0);
+
+  // One call to DidProcessTask from the first no-op task and once call to
+  // WillProcessTask before the RemoveObserverTask.
+  EXPECT_CALL(observer, WillProcessTask(_)).Times(1);
+  EXPECT_CALL(observer, DidProcessTask(_)).Times(1);
+  test_task_runner_->RunUntilIdle();
+}
+
 }  // namespace
 }  // namespace content