Reject frames with invalid BeginFrameAck in CompositorFrameSinkSupport

cc/test/compositor_frame_helpers.cc

Index: cc/test/compositor_frame_helpers.cc
diff --git a/cc/test/compositor_frame_helpers.cc b/cc/test/compositor_frame_helpers.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4cccf85caed05489cfe379e1598ff7c08257e183
--- /dev/null
+++ b/cc/test/compositor_frame_helpers.cc
@@ -0,0 +1,20 @@
+// Copyright 2017 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/compositor_frame_helpers.h"
+#include "cc/output/compositor_frame.h"
+
+namespace cc {
+namespace test {
+
+CompositorFrame MakeCompositorFrame() {
+  CompositorFrame frame;
+  frame.metadata.begin_frame_ack.source_id = BeginFrameArgs::kManualSourceId;
+  frame.metadata.begin_frame_ack.sequence_number =
+      BeginFrameArgs::kStartingFrameNumber;
+  return frame;
+}
+
+}  // namespace test
+}  // namespace cc