Implement Chromium side of MediaKeys.isTypeSupported().

content/public/renderer/key_system_info.h

Index: content/public/renderer/key_system_info.h
diff --git a/content/public/renderer/key_system_info.h b/content/public/renderer/key_system_info.h
index 8eb2e573c4806e7e4fb1284bbe7929155628450c..9ec317d4bdc998863bbb07a0dc225b5f2e1fbfee 100644
--- a/content/public/renderer/key_system_info.h
+++ b/content/public/renderer/key_system_info.h
@@ -11,7 +11,7 @@
 #include "base/basictypes.h"
 #include "base/containers/hash_tables.h"
 #include "content/common/content_export.h"
-#include "content/public/common/eme_codec.h"
+#include "content/public/common/eme_constants.h"
 
 // Definitions:
 // * Key system
@@ -38,6 +38,9 @@ struct CONTENT_EXPORT KeySystemInfo {
 
   std::string key_system;
 
+  // Specifies registered initialization data types supported by |key_system|.
+  SupportedInitDataTypes supported_init_data_types;
+
   // Specifies codecs supported by |key_system|.
   SupportedCodecs supported_codecs;