Fix encrypted content handling in VaapiVideoDecoder

The USE flag for CHROMEOS_PROTECTED_MEDIA will be turned on before we
have encrypted content handling done here, so reject that config in all
cases until that is done.

BUG=b:153111783
TEST=Builds

Change-Id: Ibcd83a91ab83ef30afd01bbe7db6b5c792f474a7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2495801
Auto-Submit: Jeffrey Kardatzke <jkardatzke@google.com>
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: Xiaohan Wang <xhwang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#820482}

media/gpu/vaapi/vaapi_video_decoder.cc

@@ -143,16 +143,11 @@ void VaapiVideoDecoder::Initialize(const VideoDecoderConfig& config,
     return;
   }
 
-#if BUILDFLAG(USE_CHROMEOS_PROTECTED_MEDIA)
-  // TODO(jkardatzke): Implement protected media handling.
-  NOTREACHED();
-#else
   if (cdm_context || config.is_encrypted()) {
     VLOGF(1) << "Vaapi decoder does not support encrypted stream";
     std::move(init_cb).Run(StatusCode::kEncryptedContentUnsupported);
     return;
   }
-#endif
 
   // We expect the decoder to have released all output buffers (by the client
   // triggering a flush or reset), even if the