Add API for getting page labels.

public/fpdf_doc.h

Index: public/fpdf_doc.h
diff --git a/public/fpdf_doc.h b/public/fpdf_doc.h
index 9d2229c0c1d0f2435aaaf79e2fcd0823a727de7b..b245d46900032529d0e28ef2ebfbc3f83aa5108c 100644
--- a/public/fpdf_doc.h
+++ b/public/fpdf_doc.h
@@ -281,26 +281,43 @@ DLLEXPORT FPDF_BOOL STDCALL FPDFLink_GetQuadPoints(FPDF_LINK linkAnnot,
 
 // Get meta-data |tag| content from |document|.
 //
-//   doc    - handle to the document
-//   tag    - the tag to retrieve. The tag can be one of:
-//              Title, Author, Subject, Keywords, Creator, Producer,
-//              CreationDate, or ModDate.
-//            For detailed explanations of these tags and their respective
-//            values, please refer to PDF Reference 1.6, section 10.2.1,
-//            'Document Information Dictionary'.
-//   buffer - a buffer for the title. May be NULL.
-//   buflen - the length of the buffer, in bytes. May be 0.
+//   document - handle to the document.
+//   tag      - the tag to retrieve. The tag can be one of:
+//                Title, Author, Subject, Keywords, Creator, Producer,
+//                CreationDate, or ModDate.
+//              For detailed explanations of these tags and their respective
+//              values, please refer to PDF Reference 1.6, section 10.2.1,
+//              'Document Information Dictionary'.
+//   buffer   - a buffer for the tag. May be NULL.
+//   buflen   - the length of the buffer, in bytes. May be 0.
 //
-// Returns the number of bytes in the title, including trailing zeros.
+// Returns the number of bytes in the tag, including trailing zeros.
 //
 // The |buffer| is always encoded in UTF-16LE. The |buffer| is followed by two
 // bytes of zeros indicating the end of the string.  If |buflen| is less than
 // the returned length, or |buffer| is NULL, |buffer| will not be modified.
-DLLEXPORT unsigned long STDCALL FPDF_GetMetaText(FPDF_DOCUMENT doc,
+DLLEXPORT unsigned long STDCALL FPDF_GetMetaText(FPDF_DOCUMENT document,
                                                  FPDF_BYTESTRING tag,
                                                  void* buffer,
                                                  unsigned long buflen);
 
+// Get the page label for |page_index| from |document|.
+//
+//   document    - handle to the document.
+//   page_index  - the 0-based index of the page.
+//   buffer      - a buffer for the page label. May be NULL.
+//   buflen      - the length of the buffer, in bytes. May be 0.
+//
+// Returns the number of bytes in the page label, including trailing zeros.
+//
+// The |buffer| is always encoded in UTF-16LE. The |buffer| is followed by two
+// bytes of zeros indicating the end of the string.  If |buflen| is less than
+// the returned length, or |buffer| is NULL, |buffer| will not be modified.
+DLLEXPORT unsigned long STDCALL FPDF_GetPagelLabel(FPDF_DOCUMENT document,
+                                                   int page_index,
+                                                   void* buffer,
+                                                   unsigned long buflen);
+
 #ifdef __cplusplus
 }  // extern "C"
 #endif  // __cplusplus