Make TestSimpleTaskRunner thread-safe.

base/test/test_simple_task_runner.h

Index: base/test/test_simple_task_runner.h
diff --git a/base/test/test_simple_task_runner.h b/base/test/test_simple_task_runner.h
index 338c634c8d9d5533ecf94ef8364ef19d36620d35..eb600f40c3a68c9396614537993f1468b138b0bb 100644
--- a/base/test/test_simple_task_runner.h
+++ b/base/test/test_simple_task_runner.h
@@ -10,8 +10,9 @@
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/single_thread_task_runner.h"
+#include "base/synchronization/lock.h"
 #include "base/test/test_pending_task.h"
-#include "base/threading/thread_checker.h"
+#include "base/threading/platform_thread.h"
 
 namespace base {
 
@@ -25,8 +26,6 @@ class TimeDelta;
 //
 // TestSimpleTaskRunner has the following properties which make it simple:
 //
-//   - It is non-thread safe; all member functions must be called on
-//     the same thread.
 //   - Tasks are simply stored in a queue in FIFO order, ignoring delay
 //     and nestability.
 //   - Tasks aren't guaranteed to be destroyed immediately after
@@ -36,10 +35,6 @@ class TimeDelta;
 // handles the running of tasks that in turn call back into itself
 // (e.g., to post more tasks).
 //
-// If you need more complicated properties, consider using this class
-// as a template for writing a test TaskRunner implementation using
-// TestPendingTask.
-//
 // Note that, like any TaskRunner, TestSimpleTaskRunner is
 // ref-counted.
 class TestSimpleTaskRunner : public SingleThreadTaskRunner {
@@ -56,27 +51,35 @@ class TestSimpleTaskRunner : public SingleThreadTaskRunner {
 
   bool RunsTasksOnCurrentThread() const override;
 
-  const std::deque<TestPendingTask>& GetPendingTasks() const;
+  std::deque<TestPendingTask> GetPendingTasks() const;
+  size_t NumPendingTasks() const;
   bool HasPendingTask() const;
   base::TimeDelta NextPendingTaskDelay() const;
 
   // Clears the queue of pending tasks without running them.
   void ClearPendingTasks();
 
-  // Runs each current pending task in order and clears the queue.
-  // Any tasks posted by the tasks are not run.
-  virtual void RunPendingTasks();
+  // Runs each current pending task in order and clears the queue. Tasks posted
+  // by the tasks that run within this call do not run within this call. Can
+  // only be called on the thread that created this TestSimpleTaskRunner.
+  void RunPendingTasks();
 
-  // Runs pending tasks until the queue is empty.
+  // Runs pending tasks until the queue is empty. Can only be called on the
+  // thread that created this TestSimpleTaskRunner.
   void RunUntilIdle();
 
  protected:
   ~TestSimpleTaskRunner() override;

[danakj, 2016/09/01 21:22:18]

nit: idk why this is protected.. maybe make this public while you're here?

[fdoray, 2016/09/02 17:39:16]

TestSimpleTaskRunner is ref-counted. Having a protected destructor ensures that
nobody deletes it explicitly. Since TestSimpleTaskRunner has derived classes,
its destructor can't be private.

[danakj, 2016/09/02 20:00:07]

Oh I missed that since it's inheriting that. Thanks.

 
+ private:
+  // Thread on which this was instantiated.
+  const PlatformThreadRef thread_ref_ = PlatformThread::CurrentRef();
+
+  // Synchronizes access to |pending_tasks_|.
+  mutable Lock lock_;
+
   std::deque<TestPendingTask> pending_tasks_;
-  ThreadChecker thread_checker_;
 
- private:
   DISALLOW_COPY_AND_ASSIGN(TestSimpleTaskRunner);
 };