Change initDataType and sessionType to be enums

public/platform/WebMediaPlayerClient.h

Index: public/platform/WebMediaPlayerClient.h
diff --git a/public/platform/WebMediaPlayerClient.h b/public/platform/WebMediaPlayerClient.h
index 524fa6c19dd5abf08ad05a0031274f946f7f21a3..38516f9d6dcffb9ccbfa1a5528eda5df41faa222 100644
--- a/public/platform/WebMediaPlayerClient.h
+++ b/public/platform/WebMediaPlayerClient.h
@@ -32,6 +32,7 @@
 #define WebMediaPlayerClient_h
 
 #include "WebMediaPlayer.h"
+#include "public/platform/WebEncryptedMediaTypes.h"
 
 namespace blink {
 
@@ -81,6 +82,8 @@ public:
     virtual void keyAdded(const WebString& keySystem, const WebString& sessionId) = 0;
     virtual void keyError(const WebString& keySystem, const WebString& sessionId, MediaKeyErrorCode, unsigned short systemCode) = 0;
     virtual void keyMessage(const WebString& keySystem, const WebString& sessionId, const unsigned char* message, unsigned messageLength, const WebURL& defaultURL) = 0;
+    virtual void encrypted(WebEncryptedMediaInitDataType, const unsigned char* initData, unsigned initDataLength) = 0;
+    // FIXME: Remove this once Chromium updated to use enum type.
     virtual void encrypted(const WebString& initDataType, const unsigned char* initData, unsigned initDataLength) = 0;
     virtual void didBlockPlaybackWaitingForKey() = 0;
     virtual void didResumePlaybackBlockedForKey() = 0;