Prevent depacketizer OOB reads on zero-length VP8 payload.

webrtc/modules/rtp_rtcp/source/rtp_format_vp8_unittest.cc

Index: webrtc/modules/rtp_rtcp/source/rtp_format_vp8_unittest.cc
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_format_vp8_unittest.cc b/webrtc/modules/rtp_rtcp/source/rtp_format_vp8_unittest.cc
index 804dc0903884eab16aa382c994229fab110b3d69..4283a778d00a072359b384ac6da1f0b92e0d8500 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_format_vp8_unittest.cc
+++ b/webrtc/modules/rtp_rtcp/source/rtp_format_vp8_unittest.cc
@@ -596,4 +596,11 @@ TEST_F(RtpDepacketizerVp8Test, TestWithPacketizer) {
   EXPECT_EQ(payload.type.Video.codecHeader.VP8.layerSync,
             input_header.layerSync);
 }
+
+TEST_F(RtpDepacketizerVp8Test, TestEmptyPayload) {
+  // Using a wild pointer to crash on accesses from inside the depacketizer.
+  uint8_t* garbage_ptr = reinterpret_cast<uint8_t*>(0x4711);
+  RtpDepacketizer::ParsedPayload payload;
+  EXPECT_FALSE(depacketizer_->Parse(&payload, garbage_ptr, 0));
+}
 }  // namespace webrtc