Revert "Remove MediaKeys.isTypeSupported()."

LayoutTests/media/encrypted-media/encrypted-media-utils.js

 var console = null;
 
 function consoleWrite(text)
 {
     if (!console && document.body) {
         console = document.createElement('div');
         document.body.appendChild(console);
     }
     var span = document.createElement('span');
     span.appendChild(document.createTextNode(text));
     span.appendChild(document.createElement('br'));
     console.appendChild(span);
 }
 
-// FIXME: Detect EME support rather than just general container support.
-// http://crbug.com/441585
-// For now, assume that implementations that support a container type for clear
-// content and are running these tests also support that container with EME.
-// Because this code creates an ActiveDOMObject, which could break the lifetime
-// tests, we must run it before the actual tests run and save the results for
-// use in the tests.
-var element = new Audio();
-var isWebMSupported = ('' != element.canPlayType('video/webm'));
-var isCencSupported = ('' != element.canPlayType('video/mp4'));
-// Force the ActiveDOMObject to be deleted before the tests run.
-element = null;
-asyncGC();
-
-function isInitDataTypeSupported(initDataType)
-{
-    var result = false;
-    switch (initDataType) {
-    case 'webm':
-        result = isWebMSupported;
-        break;
-    case 'cenc':
-        result = isCencSupported;
-        break;
-    default:
-        result = false;
-    }
-
-    return result;
-}
-
-
 function getInitDataType()
 {
-    if (isInitDataTypeSupported('webm'))
-        return 'webm';
-    if (isInitDataTypeSupported('cenc'))
-        return 'cenc';
-    throw 'No supported Initialization Data Types';
+    return (MediaKeys.isTypeSupported('org.w3.clearkey', 'video/webm')) ? 'webm' : 'cenc';
 }
 
 function getInitData(initDataType)
 {
     // FIXME: This should be dependent on initDataType.
     return new Uint8Array([ 0, 1, 2, 3, 4, 5, 6, 7 ]);
 }
 
 function waitForEventAndRunStep(eventName, element, func, stepTest)
 {
@@ skipping 109 matching lines @@
         return stringToUint8Array(decoded_key);
     }
     catch (o) {
         // Not valid JSON, so return message untouched as Uint8Array.
         // This is for backwards compatibility.
         // FIXME: Remove this once the code is switched to return JSON all
         // the time.
         return new Uint8Array(message);
     }
 }