build pdf resources from submodule

electron.gyp

@@ -427,7 +427,7 @@
           'action_name': 'pdfviewer',
           'inputs': [
             '<(grit_dir)/grit.py',
-            '<@(pdf_viewer_sources)',
+            'vendor/pdf_viewer/resources.grd',
           ],
           'outputs': [
             'pdf_viewer_resouces.h',
@@ -439,7 +439,7 @@
             'python',
             '<(grit_dir)/grit.py',
             '-i',
-            '<@(pdf_viewer_sources)',
+            'vendor/pdf_viewer/resources.grd',
             'build',
             '-o',
             '<(SHARED_INTERMEDIATE_DIR)/grit',

filenames.gypi

@@ -96,9 +96,6 @@
       'default_app/main.js',
       'default_app/package.json',
     ],
-    'pdf_viewer_sources': [
-      'atom/browser/resources/pdf_viewer/resources.grd',
-    ],
     'lib_sources': [
       'atom/app/atom_content_client.cc',
       'atom/app/atom_content_client.h',