Change initDataType and sessionType to be enums

public/platform/WebContentDecryptionModuleSession.h

Index: public/platform/WebContentDecryptionModuleSession.h
diff --git a/public/platform/WebContentDecryptionModuleSession.h b/public/platform/WebContentDecryptionModuleSession.h
index 7b98366d49134b55882f743f13c26355cc587fc8..8fa3c959f970bb0abdd59b6359d39d1b04c05e40 100644
--- a/public/platform/WebContentDecryptionModuleSession.h
+++ b/public/platform/WebContentDecryptionModuleSession.h
@@ -35,6 +35,7 @@
 #include "WebVector.h"
 #include "public/platform/WebContentDecryptionModuleException.h"
 #include "public/platform/WebContentDecryptionModuleResult.h"
+#include "public/platform/WebEncryptedMediaTypes.h"
 
 namespace blink {
 
@@ -76,6 +77,8 @@ public:
     virtual void setClientInterface(Client*) = 0;
     virtual WebString sessionId() const = 0;
 
+    virtual void initializeNewSession(WebEncryptedMediaInitDataType, const unsigned char* initData, size_t initDataLength, WebEncryptedMediaSessionType, WebContentDecryptionModuleResult);
+    // FIXME: remove this version once Chromium updated to pass enums.
     virtual void initializeNewSession(const WebString& initDataType, const unsigned char* initData, size_t initDataLength, const WebString& sessionType, WebContentDecryptionModuleResult) = 0;
     virtual void load(const WebString& sessionId, WebContentDecryptionModuleResult) = 0;
     virtual void update(const unsigned char* response, size_t responseLength, WebContentDecryptionModuleResult) = 0;