Add presubmit check to prevent package boundary violations.

tools-webrtc/testdata/subdir/subdir2/dummy3.h

Index: tools-webrtc/testdata/subdir/subdir2/dummy3.h
diff --git a/tools-webrtc/testdata/subdir/subdir2/dummy3.h b/tools-webrtc/testdata/subdir/subdir2/dummy3.h
new file mode 100644
index 0000000000000000000000000000000000000000..6c39af9a7ccfeb2b9ef661c528246d60515b14bb
--- /dev/null
+++ b/tools-webrtc/testdata/subdir/subdir2/dummy3.h
@@ -0,0 +1,11 @@
+// Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the LICENSE file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS.  All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+
+#ifndef TOOLS_WEBRTC_TESTDATA_SUBDIR_SUBDIR2_DUMMY3_H_
+#define TOOLS_WEBRTC_TESTDATA_SUBDIR_SUBDIR2_DUMMY3_H_
+#endif  // TOOLS_WEBRTC_TESTDATA_SUBDIR_SUBDIR2_DUMMY3_H_