sprang@, would you mind taking a look?

Please note that this crash has been found using Debug build.

DCHECK on input buffer.
will remove it, it doesn't guard against any bigger problems.

The following revision refers to this bug:
  https://chromium.googlesource.com/external/webrtc.git/+/20fcbf15f063d43acc3ad3d4c5134b92644dc13f

commit 20fcbf15f063d43acc3ad3d4c5134b92644dc13f
Author: Danil Chapovalov <danilchap@webrtc.org>
Date: Wed Aug 31 16:47:16 2016

Remove faulty DCHECK in rtcp::TransportFeedback  DecodeSymbol

BUG= chromium:642745 
R=sprang@webrtc.org

Review URL: https://codereview.webrtc.org/2296953003 .

Cr-Commit-Position: refs/heads/master@{#14003}

[modify] https://crrev.com/20fcbf15f063d43acc3ad3d4c5134b92644dc13f/webrtc/modules/rtp_rtcp/source/rtcp_packet/transport_feedback.cc

ClusterFuzz has detected this issue as fixed in range 416193:416227.

Detailed report: https://cluster-fuzz.appspot.com/testcase?key=4757950503845888

Fuzzer: libfuzzer_rtcp_receiver_fuzzer
Job Type: libfuzzer_chrome_asan_debug
Platform Id: linux

Crash Type: UNKNOWN
Crash Address: 0x03e9000047e5
Crash State:
  webrtc::rtcp::DecodeSymbol
  webrtc::rtcp::TwoBitVectorChunk::ParseFrom
  webrtc::rtcp::TransportFeedback::ParseChunk
  
Regressed: https://cluster-fuzz.appspot.com/revisions?job=libfuzzer_chrome_asan_debug&range=395717:395804
Fixed: https://cluster-fuzz.appspot.com/revisions?job=libfuzzer_chrome_asan_debug&range=416193:416227

Minimized Testcase (0.03 Kb): https://cluster-fuzz.appspot.com/download/AMIfv956_w0JDbqRXmKyBjjooAND5PdHiZZ0mQqKnXXGbpykFpI4xa1Q8b-Q5Np8Md-vTUh9gscU-l2tWsDzf6Z7npX_9QFBCUOP_JzcEVDVc0J41eGO7gHZQxw596zChB5mjXvhp0hbZcOrx4wRec-SWr-m_aNW6A?testcase_id=4757950503845888

Additional requirements: Requires Gestures

See https://chromium.googlesource.com/chromium/src/+/master/testing/libfuzzer/reproducing.md for more information.

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.

ClusterFuzz testcase is verified as fixed, closing issue.

If this is incorrect, please add ClusterFuzz-Wrong label and re-open the issue.

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