Fixing and enhancing OrderedSimpleTaskRunner to allow 100% deterministic tests.

cc/test/scheduler_test_common.cc

Index: cc/test/scheduler_test_common.cc
diff --git a/cc/test/scheduler_test_common.cc b/cc/test/scheduler_test_common.cc
index 3b35a54a9b713423dd91c55b428dc6997937f01c..00c661a545f6876bc93b1877573cb8ed6a73c87f 100644
--- a/cc/test/scheduler_test_common.cc
+++ b/cc/test/scheduler_test_common.cc
@@ -14,4 +14,42 @@ void FakeTimeSourceClient::OnTimerTick() {
 
 base::TimeTicks FakeDelayBasedTimeSource::Now() const { return now_; }
 
+void TestDelayBasedTimeSource::SetNow(base::TimeTicks time) {
+  test_task_runner_->SetNow(time);
+}
+
+std::string TestDelayBasedTimeSource::TypeString() const {
+  return "TestDelayBasedTimeSource";
+}
+
+base::TimeTicks TestDelayBasedTimeSource::Now() const {
+  return test_task_runner_->Now();
+}
+
+base::TimeTicks TestScheduler::Now() const {
+  return test_task_runner_->Now();
+}
+
+TestScheduler::TestScheduler(
+    SchedulerClient* client,
+    const SchedulerSettings& scheduler_settings,
+    int layer_tree_host_id,
+    const scoped_refptr<OrderedSimpleTaskRunner>& test_task_runner)
+    : Scheduler(client,
+                scheduler_settings,
+                layer_tree_host_id,
+                test_task_runner),
+      test_task_runner_(test_task_runner.get()) {
+  if (!settings_.begin_frame_scheduling_enabled) {
+    scoped_refptr<DelayBasedTimeSource> time_source =
+        TestDelayBasedTimeSource::Create(VSyncInterval(), test_task_runner_);
+    synthetic_begin_frame_source_.reset(
+        new SyntheticBeginFrameSource(this, time_source));
+  }
+}
+
+void TestScheduler::SetNow(base::TimeTicks time) {
+  test_task_runner_->SetNow(time);
+}
+
 }  // namespace cc