Implement "Key Presence" step in "Encrypted Block Encounted" algorithm in EME.

media/filters/ffmpeg_video_decoder.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/filters/ffmpeg_video_decoder.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/bind.h"
@@ skipping 342 matching lines @@
   DCHECK_NE(state_, kUninitialized);
   DCHECK_NE(state_, kDecodeFinished);
   DCHECK(!read_cb_.is_null());
 
   if (!reset_cb_.is_null()) {
     base::ResetAndReturn(&read_cb_).Run(kOk, NULL);
     DoReset();
     return;
   }
 
-  if (decrypt_status == Decryptor::kError) {
+  if (decrypt_status == Decryptor::kNoKey ||
+      decrypt_status == Decryptor::kError) {
     state_ = kDecodeFinished;
     base::ResetAndReturn(&read_cb_).Run(kDecryptError, NULL);
     return;
   }
 
   DCHECK_EQ(Decryptor::kSuccess, decrypt_status);
   DCHECK(buffer);
   DCHECK(buffer->GetDataSize());
   DCHECK(!buffer->GetDecryptConfig());
   DecodeBuffer(buffer);
@@ skipping 167 matching lines @@
     av_free(codec_context_);
     codec_context_ = NULL;
   }
   if (av_frame_) {
     av_free(av_frame_);
     av_frame_ = NULL;
   }
 }
 
 }  // namespace media