Implement Chromium side of MediaKeys.isTypeSupported().

components/cdm/renderer/android_key_systems.cc

Index: components/cdm/renderer/android_key_systems.cc
diff --git a/components/cdm/renderer/android_key_systems.cc b/components/cdm/renderer/android_key_systems.cc
index 99bc2bb5149db002453abca79267d494d2e57f7b..b77ec6450f533b53fa1f34df8f5b54f01c5e17cd 100644
--- a/components/cdm/renderer/android_key_systems.cc
+++ b/components/cdm/renderer/android_key_systems.cc
@@ -10,6 +10,7 @@
 #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_constants.h"
 #include "content/public/renderer/render_thread.h"
 
 #include "widevine_cdm_version.h"  // In SHARED_INTERMEDIATE_DIR.
@@ -65,6 +66,12 @@ void AddAndroidPlatformKeySystems(
     if (response.compositing_codecs != content::EME_CODEC_NONE) {
       KeySystemInfo info(*it);
       info.supported_codecs = response.compositing_codecs;
+      // Assume that WebM and CENC init data types are supported by platform
+      // CDMs. KeySystems validates that they match with the chosen container.

[ddorwin, 2014/09/27 00:41:24]

Check the container like the next file. The fact that ITS() will check is too
fragile and may not always be true.

[sandersd (OOO until July 31), 2014/09/29 17:49:23]

Done.

+      info.supported_init_data_types = content::EME_INIT_DATA_TYPE_WEBM;
+#if defined(USE_PROPRIETARY_CODECS)
+      info.supported_init_data_types |= content::EME_INIT_DATA_TYPE_CENC;
+#endif  // defined(USE_PROPRIETARY_CODECS)
       concrete_key_systems->push_back(info);
     }
   }