Validate references of frames inserted into FrameBuffer2.

webrtc/modules/video_coding/frame_buffer2_unittest.cc

 /*
  *  Copyright (c) 2016 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.
  */
 
@@ skipping 513 matching lines @@
   EXPECT_EQ(41248, InsertFrame(41248, 0, 1, false));
   ExtractFrame();
 }
 
 TEST_F(TestFrameBuffer2, DuplicateFrames) {
   EXPECT_EQ(22256, InsertFrame(22256, 0, 1, false));
   ExtractFrame();
   EXPECT_EQ(22256, InsertFrame(22256, 0, 1, false));
 }
 
+// TODO(philipel): implement more unittests related to invalid references.
+TEST_F(TestFrameBuffer2, InvalidReferences) {
+  EXPECT_EQ(-1, InsertFrame(0, 0, 1000, false, 2));
+  EXPECT_EQ(1, InsertFrame(1, 0, 2000, false));
+  ExtractFrame();
+  EXPECT_EQ(2, InsertFrame(2, 0, 3000, false, 1));
+}
+
 }  // namespace video_coding
 }  // namespace webrtc