Change the JS app.viewerType() return value to "pdfium"

fpdfsdk/src/javascript/app.cpp

 // 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
 
 #include "../../../third_party/base/nonstd_unique_ptr.h"
 #include "../../include/javascript/JavaScript.h"
 #include "../../include/javascript/IJavaScript.h"
 #include "../../include/javascript/JS_Define.h"
@@ skipping 170 matching lines @@
     return TRUE;
   }
 
   return FALSE;
 }
 
 FX_BOOL app::viewerType(IFXJS_Context* cc,
                         CJS_PropValue& vp,
                         CFX_WideString& sError) {
   if (vp.IsGetting()) {
-    vp << L"unknown";
+    vp << L"pdfium";
     return TRUE;
   }
 
   return FALSE;
 }
 
 FX_BOOL app::viewerVariation(IFXJS_Context* cc,
                              CJS_PropValue& vp,
                              CFX_WideString& sError) {
   if (vp.IsGetting()) {
@@ skipping 654 matching lines @@
                    CFX_WideString& sError) {
   return FALSE;
 }
 
 FX_BOOL app::execDialog(IFXJS_Context* cc,
                         const CJS_Parameters& params,
                         CJS_Value& vRet,
                         CFX_WideString& sError) {
   return TRUE;
 }