external/libvpx/libwebm: Update snapshot

Update libwebm snapshot. This update contains security fixes from upstream.

Upstream git hash: 229f49347d19b0ca0941e072b199a242ef6c5f2b

BUG=23167726

Change-Id: Id3e140e7b31ae11294724b1ecfe2e9c83b4d4207
(cherry picked from commit d0281a15b3c6bd91756e453cc9398c5ef412d99a)

long Cluster::GetNext(const BlockEntry* pCurr, const BlockEntry*& pNext) const {
  assert(pCurr);
  assert(m_entries);
  assert(m_entries_count > 0);

 size_t idx = pCurr->GetIndex();
  assert(idx < size_t(m_entries_count));
  assert(m_entries[idx] == pCurr);

 ++idx;

 if (idx >= size_t(m_entries_count)) {
 long long pos;
 long len;

 const long status = Parse(pos, len);

 if (status < 0) { // error
      pNext = NULL;
 return status;
 }

 if (status > 0) {
      pNext = NULL;
 return 0;
 }

    assert(m_entries);
    assert(m_entries_count > 0);
    assert(idx < size_t(m_entries_count));
 }

  pNext = m_entries[idx];
  assert(pNext);

 return 0;
}

long Cluster::GetNext(const BlockEntry* pCurr, const BlockEntry*& pNext) const {
  assert(pCurr);
  assert(m_entries);
  assert(m_entries_count > 0);

 size_t idx = pCurr->GetIndex();
  assert(idx < size_t(m_entries_count));
  assert(m_entries[idx] == pCurr);

 ++idx;

 if (idx >= size_t(m_entries_count)) {
 long long pos;
 long len;

 const long status = Parse(pos, len);

 if (status < 0) { // error
      pNext = NULL;
 return status;
 }

 if (status > 0) {
      pNext = NULL;
 return 0;
 }

    assert(m_entries);
    assert(m_entries_count > 0);
    assert(idx < size_t(m_entries_count));
 }

  pNext = m_entries[idx];
  assert(pNext);

 return 0;
}
