Implement Chromium side of MediaKeys.isTypeSupported().

components/cdm/renderer/android_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/android_key_systems.h"
 
 #include <string>
 #include <vector>
 
 #include "base/logging.h"
 #include "components/cdm/common/cdm_messages_android.h"
 #include "components/cdm/renderer/widevine_key_systems.h"
+#include "content/public/common/eme_codec.h"
+#include "content/public/common/eme_init_data_type.h"
 #include "content/public/renderer/render_thread.h"
 
 #include "widevine_cdm_version.h"  // In SHARED_INTERMEDIATE_DIR.
 
 using content::KeySystemInfo;
 using content::SupportedCodecs;
 
 namespace cdm {
 
 static SupportedKeySystemResponse QueryKeySystemSupport(
@@ skipping 35 matching lines @@
   std::vector<std::string> key_system_names;
   content::RenderThread::Get()->Send(
       new ChromeViewHostMsg_GetPlatformKeySystemNames(&key_system_names));
 
   for (std::vector<std::string>::const_iterator it = key_system_names.begin();
        it != key_system_names.end(); ++it) {
     SupportedKeySystemResponse response = QueryKeySystemSupport(*it);
     if (response.compositing_codecs != content::EME_CODEC_NONE) {
       KeySystemInfo info(*it);
       info.supported_codecs = response.compositing_codecs;
+      // The MediaDrm API doesn't expose initDataTypes, but platform CDMs are
+      // not really trusted to implement them in a spec-compliant way anyway.

[ddorwin, 2014/09/13 01:20:44]

It's the key systems we're concerned about in this respect.

I think you could add CENC | WEBM, and let the supported containers (represented
by codecs???) determine which is actually exposed (by the logic that ensures
only logical combinations are reported as supported).

The current code would prevent anything beyond the key system name from being
checked.

[sandersd (OOO until July 31), 2014/09/22 23:45:52]

Done.

+      info.supported_init_data_types = content::EME_INIT_DATA_TYPE_NONE;
       concrete_key_systems->push_back(info);
     }
   }
 }
 
 }  // namespace cdm