cc: Implement test task runner for tests.

cc/test/simple_task_runner.cc

Index: cc/test/simple_task_runner.cc
diff --git a/cc/test/simple_task_runner.cc b/cc/test/simple_task_runner.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5b245689cf9aed17b779ffd806dcdeec985e13ea
--- /dev/null
+++ b/cc/test/simple_task_runner.cc
@@ -0,0 +1,40 @@
+// Copyright 2016 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 "cc/test/simple_task_runner.h"
+
+#include "base/logging.h"
+
+namespace cc {
+
+void SimpleTaskRunner::ProcessTask(TileTask* task) {
+  ScheduleTask(task);
+  RunTask(task);
+  CompleteTask(task);
+}
+
+void SimpleTaskRunner::ScheduleTask(TileTask* task) {
+  DCHECK(task);
+  task->state().DidSchedule();
+}
+
+void SimpleTaskRunner::CancelTask(TileTask* task) {
+  DCHECK(task);
+  task->state().DidCancel();
+}
+
+void SimpleTaskRunner::RunTask(TileTask* task) {
+  DCHECK(task);
+  task->state().DidStart();
+  task->RunOnWorkerThread();
+  task->state().DidFinish();
+}
+
+void SimpleTaskRunner::CompleteTask(TileTask* task) {
+  DCHECK(task);
+  DCHECK(task->state().IsFinished() || task->state().IsCanceled());
+  task->OnTaskCompleted();
+}
+
+}  // namespace cc