Fixed command line parting when no output is needed.

R=bo_xu@foxitsoftware.com

Review URL: https://codereview.chromium.org/492523002

samples/pdfium_test.cc

diff --git a/samples/pdfium_test.cc b/samples/pdfium_test.cc
index 9a6513d..e92d7a1 100644
--- a/samples/pdfium_test.cc
+++ b/samples/pdfium_test.cc
@@ -198,7 +198,8 @@
     if (strcmp(argv[cur_arg], "--bmp") == 0)
       *output_format = OUTPUT_BMP;
 #endif
-    cur_arg++;
+    if (*output_format != OUTPUT_NONE)
+      cur_arg++;
   }
 
   if (cur_arg >= argc)