VP8DecoderImpl: Fix uninitialized memory crash

webrtc/modules/video_coding/codecs/vp8/vp8_impl.cc

Index: webrtc/modules/video_coding/codecs/vp8/vp8_impl.cc
diff --git a/webrtc/modules/video_coding/codecs/vp8/vp8_impl.cc b/webrtc/modules/video_coding/codecs/vp8/vp8_impl.cc
index 2e510ec897fbb9f8c2c8e1b6b801107b475987a2..b6b463cb398c62d5edeed311d2513220cd35f300 100644
--- a/webrtc/modules/video_coding/codecs/vp8/vp8_impl.cc
+++ b/webrtc/modules/video_coding/codecs/vp8/vp8_impl.cc
@@ -1080,6 +1080,7 @@ int VP8DecoderImpl::InitDecode(const VideoCodec* inst, int number_of_cores) {
   }
   if (decoder_ == NULL) {
     decoder_ = new vpx_codec_ctx_t;
+    memset(decoder_, 0, sizeof(*decoder_));
   }
   if (inst && inst->codecType == kVideoCodecVP8) {
     feedback_mode_ = inst->VP8().feedbackModeOn;
@@ -1096,6 +1097,8 @@ int VP8DecoderImpl::InitDecode(const VideoCodec* inst, int number_of_cores) {
 #endif
 
   if (vpx_codec_dec_init(decoder_, vpx_codec_vp8_dx(), &cfg, flags)) {
+    delete decoder_;
+    decoder_ = nullptr;
     return WEBRTC_VIDEO_CODEC_MEMORY;
   }