Fix a typo with PAGEMODE_UNKNOWN.

fpdfsdk/include/fpdf_ext.h

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
  
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #ifndef _FPDF_EXT_H_
 #define _FPDF_EXT_H_
 
 #ifndef _FPDFVIEW_H_
@@ skipping 53 matching lines @@
  *                      unsp_info               -       Pointer to a UNSUPPORT_INFO structure.
  * Return Value:
  *                      TRUE means successful. FALSE means fails. 
  **/
 
 DLLEXPORT FPDF_BOOL STDCALL FSDK_SetUnSpObjProcessHandler(UNSUPPORT_INFO* unsp_info);
 
 //flags for page mode. 
 
 //Unknown value
-#define PAGEMODE_UNKONOWN               -1
+#define PAGEMODE_UNKNOWN                -1
 
 //Neither document outline nor thumbnail images visible
 #define PAGEMODE_USENONE                0
 
 //Document outline visible
 #define PAGEMODE_USEOUTLINES    1
 
 //Thumbnial images visible
 #define PAGEMODE_USETHUMBS              2
 
@@ skipping 14 matching lines @@
  *                      doc             -       Handle to document. Returned by FPDF_LoadDocument function.
  * Return Value:
  *                      The flags for page mode.
  **/
 DLLEXPORT int FPDFDoc_GetPageMode(FPDF_DOCUMENT document);
 
 #ifdef __cplusplus
 };
 #endif
 #endif