Drop VP8 frames in case of duplicates in RtpFrameReferenceFinder.

webrtc/modules/video_coding/rtp_frame_reference_finder_unittest.cc

Index: webrtc/modules/video_coding/rtp_frame_reference_finder_unittest.cc
diff --git a/webrtc/modules/video_coding/rtp_frame_reference_finder_unittest.cc b/webrtc/modules/video_coding/rtp_frame_reference_finder_unittest.cc
index 5fa88802a6bb03e33d964d3c097a01b559d9d343..59cf4384cab25419e959031a81d46a62c0700d32 100644
--- a/webrtc/modules/video_coding/rtp_frame_reference_finder_unittest.cc
+++ b/webrtc/modules/video_coding/rtp_frame_reference_finder_unittest.cc
@@ -428,6 +428,23 @@ TEST_F(TestRtpFrameReferenceFinder, Vp8TemporalLayers_0) {
   CheckReferencesVp8(pid + 3, pid + 2);
 }
 
+TEST_F(TestRtpFrameReferenceFinder, Vp8DuplicateTl1Frames) {
+  uint16_t pid = Rand();
+  uint16_t sn = Rand();
+
+  InsertVp8(sn, sn, true, pid, 0, 0);
+  InsertVp8(sn + 1, sn + 1, false, pid + 1, 1, 0, true);
+  InsertVp8(sn + 2, sn + 2, false, pid + 2, 0, 1);
+  InsertVp8(sn + 3, sn + 3, false, pid + 3, 1, 1);
+  InsertVp8(sn + 3, sn + 3, false, pid + 3, 1, 1);

[sprang_webrtc, 2017/03/06 09:52:52]

Should you add something new after this one to make sure it doesn't get stuck in
a weird state?

[philipel, 2017/03/07 10:47:11]

Done.

+
+  ASSERT_EQ(4UL, frames_from_callback_.size());
+  CheckReferencesVp8(pid);
+  CheckReferencesVp8(pid + 1, pid);
+  CheckReferencesVp8(pid + 2, pid);
+  CheckReferencesVp8(pid + 3, pid + 1, pid + 2);
+}
+
 // Test with 1 temporal layer.
 TEST_F(TestRtpFrameReferenceFinder, Vp8TemporalLayersReordering_0) {
   uint16_t pid = Rand();