Tidy public fpdfview.h and fpdf_flatten.h.

public/fpdf_flatten.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 PUBLIC_FPDF_FLATTEN_H_
 #define PUBLIC_FPDF_FLATTEN_H_
 
 #include "fpdfview.h"
 
+// Result codes.
 #define FLATTEN_FAIL            0   // Flatten operation failed.
 #define FLATTEN_SUCCESS         1   // Flatten operation succeed.
-#define FLATTEN_NOTINGTODO      2   // There is nothing can be flatten.
+#define FLATTEN_NOTHINGTODO     2   // There is nothing to be flattened.
+
+// Flags.
+#define FLAT_NORMALDISPLAY     0
+#define FLAT_PRINT             1
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-#define FLAT_NORMALDISPLAY     0
-#define FLAT_PRINT             1
-    //Function: FPDFPage_Flatten
-
-    //          Flat a pdf page,annotations or form fields will become part of the page contents.
-    //Parameters:
-
-    //          page  - Handle to the page. Returned by FPDF_LoadPage function.
-    //          nFlag - the flag for the use of flatten result. Zero for normal display, 1 for print.
-    //Return value:
-    //          The result flag of the function, See flags above ( FLATTEN_FAIL, FLATTEN_SUCCESS, FLATTEN_NOTINGTODO ).
-    //
-    // Comments: Current version all fails return zero. If necessary we will assign different value
-    //          to indicate different fail reason.
-    //
-    DLLEXPORT int STDCALL FPDFPage_Flatten( FPDF_PAGE page, int nFlag);
-
+// Function: FPDFPage_Flatten
+//          Make annotations and form fields become part of the page contents itself.
+// Parameters:
+//          page  - Handle to the page, as returned by FPDF_LoadPage().
+//          nFlag - Intended use of the flattened result: 0 for normal display, 1 for printing.
+// Return value:
+//          Either FLATTEN_FAIL, FLATTEN_SUCCESS, or FLATTEN_NOTHINGTODO (see above).
+// Comments:
+//          Currently, all failures return FLATTEN_FAIL, with no indication for the reason
+//          for the failure.
+DLLEXPORT int STDCALL FPDFPage_Flatten(FPDF_PAGE page, int nFlag);
 
 #ifdef __cplusplus
 }
 #endif
 
 #endif  // PUBLIC_FPDF_FLATTEN_H_