Fix fuzzer issue in H265Decoder

BUG=chrome:1148422
TEST=fuzzer test case now passes

Change-Id: I1d466d470b827249f5884cca8db9e61bdd291563
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2534153
Auto-Submit: Jeffrey Kardatzke <jkardatzke@google.com>
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Sergey Volk <servolk@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Sergey Volk <servolk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827008}

media/gpu/h265_decoder.cc

@@ -796,6 +796,9 @@ bool H265Decoder::PerformDpbOperations(const H265SPS* sps) {
           std::max(num_to_output,
                    static_cast<int>(dpb_.size()) -
                        sps->sps_max_dec_pic_buffering_minus1[highest_tid]);
+
+      num_to_output =
+          std::min(num_to_output, static_cast<int>(not_outputted.size()));
       if (!num_to_output && dpb_.IsFull()) {
         // This is wrong, we should try to output pictures until we can clear
         // one from the DPB. This is better than failing, but we then may end up