Bug 1401069 - Part 7. Declare GetPageCount as a const member function. r=fatseng

MozReview-Commit-ID: IRM8FikStJi

--HG--
extra : rebase_source : 5eb8658bc684054cc3084372cc5bf491d4db161c

widget/windows/PDFViaEMFPrintHelper.h

@@ -37,7 +37,7 @@ public:
   /** Releases document buffer. */
   void CloseDocument();
 
-  int GetPageCount() { return mPDFiumEngine->GetPageCount(mPDFDoc); }
+  int GetPageCount() const { return mPDFiumEngine->GetPageCount(mPDFDoc); }
 
   /** Convert specified PDF page to EMF and draw the EMF onto the given DC. */
   bool DrawPage(HDC aPrinterDC, unsigned int aPageIndex,