Add error struct to support the setSinkId operation for WebMediaPlayer.

public/platform/WebSetSinkIdError.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef WebSyncError_h
-#define WebSyncError_h
+#ifndef WebSetSinkIdError_h
+#define WebSetSinkIdError_h
 
 #include "public/platform/WebString.h"
 
 namespace blink {
 
-struct WebSyncError {
+struct WebSetSinkIdError {
     enum ErrorType {
-        ErrorTypeAbort = 0,
-        ErrorTypeNoPermission,
-        ErrorTypeNotFound,
-        ErrorTypeUnknown,
-        ErrorTypeLast = ErrorTypeUnknown
+        ErrorTypeNotFound = 1,
+        ErrorTypeSecurity,
+        ErrorTypeAbort,
+        ErrorTypeNotSupported,
+        ErrorTypeLast = ErrorTypeNotSupported
     };
 
-    WebSyncError(ErrorType errorType, const WebString& message)
+    WebSetSinkIdError(ErrorType errorType, const WebString& message)
         : errorType(errorType)
         , message(message)
     {
     }
 
     ErrorType errorType;
     WebString message;
 };
 
 } // namespace blink
 
-#endif // WebSyncError_h
+#endif // WebSetSinkIdError_h