Skip check for |codec_| during re-init.

During re-init, we sometimes don't have a codec.  This causes a
dcheck if we also decide to re-init the codec to increase the
input buffer size.

If there really is no codec when we re-init (e.g., if we're already
in the middle of a reallocation from a previous re-init), then we'll
just re-re-init the codec and continue.  So, just omit the DCHECK.

Bug: 1048341
Change-Id: I199c4ccdce1c169be069ab96593188de76250648
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2036277Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Frank Liberato <liberato@chromium.org>
Cr-Commit-Position: refs/heads/master@{#742260}

media/gpu/android/media_codec_video_decoder.cc

@@ -359,7 +359,6 @@ void MediaCodecVideoDecoder::Initialize(const VideoDecoderConfig& config,
     last_width_ = width;
   } else if (width > last_width_ * kReallocateThreshold && device_info_ &&
              device_info_->SdkVersion() > base::android::SDK_VERSION_P) {
-    DCHECK(codec_);
     // Reallocate the codec the next time we queue input, once there are no
     // outstanding output buffers.  Note that |deferred_flush_pending_| might
     // already be set, which is fine.  We're just upgrading the flush.