Implement Chromium side of MediaKeys.isTypeSupported().

components/cdm/renderer/widevine_key_systems.cc

 // Copyright 2014 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 "components/cdm/renderer/widevine_key_systems.h"
 
 #include <string>
 #include <vector>
 
 #include "base/logging.h"
+#include "content/public/common/eme_constants.h"
 
 #include "widevine_cdm_version.h"  // In SHARED_INTERMEDIATE_DIR.
 
 #if defined(WIDEVINE_CDM_AVAILABLE)
 
 using content::KeySystemInfo;
 using content::SupportedCodecs;
 
 namespace cdm {
 
@@ skipping 21 matching lines @@
 #endif  // defined(OS_ANDROID)
     default:
       NOTREACHED();
   }
 
   // TODO(xhwang): A container or an initDataType may be supported even though
   // there are no codecs supported in that container. Fix this when we support
   // initDataType.
   info.supported_codecs = supported_codecs;
 
+  // Here we assume that support for a container imples support for the
+  // associated initialization data type. KeySystems handles validating
+  // |init_data_type| x |container| pairings.
+  if (supported_codecs & content::EME_CODEC_WEBM_ALL)
+    info.supported_init_data_types |= content::EME_INIT_DATA_TYPE_WEBM;
+#if defined(USE_PROPRIETARY_CODECS)
+  if (supported_codecs & content::EME_CODEC_MP4_ALL)
+    info.supported_init_data_types |= content::EME_INIT_DATA_TYPE_CENC;
+#endif  // defined(USE_PROPRIETARY_CODECS)
+
 #if defined(ENABLE_PEPPER_CDMS)
   info.pepper_type = kWidevineCdmPluginMimeType;
 #endif  // defined(ENABLE_PEPPER_CDMS)
 
   concrete_key_systems->push_back(info);
 }
 
 }  // namespace cdm
 
 #endif  // defined(WIDEVINE_CDM_AVAILABLE)