Disable warning 4267 in pdfium until it is fixed.

pdfium.gyp

 {
   'variables': {
     'pdf_use_skia%': 0,
   },
   'target_defaults': {
     'defines' : [
       'FOXIT_CHROME_BUILD',
       '_FXFT_VERSION_=2501',
       '_FPDFSDK_LIB',
       '_NO_GDIPLUS_',  # workaround text rendering issues on Windows
@@ skipping 22 matching lines @@
           }],
         ],
       }],
       ['OS=="mac"', {
         'xcode_settings': {
           'GCC_ENABLE_CPP_EXCEPTIONS': 'YES',
         },
       }],
     ],
     'msvs_disabled_warnings': [
-      4005, 4018, 4146, 4333, 4345
+      4005, 4018, 4146, 4333, 4345, 4267
     ],
   },
   'targets': [
     {
       'target_name': 'pdfium',
       'type': 'static_library',
       'dependencies': [
         'safemath',
         'fdrm',
         'fpdfdoc',
@@ skipping 793 matching lines @@
         'fpdfsdk/src/formfiller/FFL_ListBox.cpp',
         'fpdfsdk/src/formfiller/FFL_Notify.cpp',
         'fpdfsdk/src/formfiller/FFL_PushButton.cpp',
         'fpdfsdk/src/formfiller/FFL_RadioButton.cpp',
         'fpdfsdk/src/formfiller/FFL_TextField.cpp',
         'fpdfsdk/src/formfiller/FFL_Utils.cpp',
       ],
     },
   ],
 }