cc: Add support for handling authoritative vsync interval

cc/scheduler/scheduler_unittest.cc

Index: cc/scheduler/scheduler_unittest.cc
diff --git a/cc/scheduler/scheduler_unittest.cc b/cc/scheduler/scheduler_unittest.cc
index b59359c03f29bd13bfa2d5f4063ff5d9b295c206..dacc03ce21ae118e553ad78b10324a5e45a3d9e9 100644
--- a/cc/scheduler/scheduler_unittest.cc
+++ b/cc/scheduler/scheduler_unittest.cc
@@ -2272,5 +2272,33 @@ TEST_F(SchedulerTest, SendBeginMainFrameNotExpectedSoon) {
   client_->Reset();
 }
 
+TEST_F(SchedulerTest, AuthoritativeVSyncInterval) {
+  SetUpScheduler(true);
+
+  base::TimeDelta initial_interval =
+      scheduler_->begin_impl_frame_args().interval;
+  base::TimeDelta authoritative_interval =
+      base::TimeDelta::FromMilliseconds(33);
+
+  scheduler_->SetNeedsCommit();
+  EXPECT_SCOPED(AdvanceFrame());
+
+  EXPECT_EQ(initial_interval, scheduler_->begin_impl_frame_args().interval);
+
+  scheduler_->NotifyBeginMainFrameStarted();
+  scheduler_->NotifyReadyToCommit();
+  task_runner().RunTasksWhile(client_->ImplFrameDeadlinePending(true));
+
+  scheduler_->SetAuthoritativeVSyncInterval(authoritative_interval);
+
+  EXPECT_SCOPED(AdvanceFrame());
+
+  // At the next BeginFrame, authoritative interval is used instead of previous
+  // interval.
+  EXPECT_NE(initial_interval, scheduler_->begin_impl_frame_args().interval);
+  EXPECT_EQ(authoritative_interval,
+            scheduler_->begin_impl_frame_args().interval);
+}
+
 }  // namespace
 }  // namespace cc