Validate references of frames inserted into FrameBuffer2.

webrtc/modules/video_coding/frame_buffer2_unittest.cc

Index: webrtc/modules/video_coding/frame_buffer2_unittest.cc
diff --git a/webrtc/modules/video_coding/frame_buffer2_unittest.cc b/webrtc/modules/video_coding/frame_buffer2_unittest.cc
index 488b7853350b7b2505369a420fadf0466bf677b5..58b3f7a42b51d91536d9e00291bc701ec73c5a7c 100644
--- a/webrtc/modules/video_coding/frame_buffer2_unittest.cc
+++ b/webrtc/modules/video_coding/frame_buffer2_unittest.cc
@@ -531,5 +531,13 @@ TEST_F(TestFrameBuffer2, DuplicateFrames) {
   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