Change grit whitelist to a string parameter

build/grit_action.gypi

Index: build/grit_action.gypi
diff --git a/build/grit_action.gypi b/build/grit_action.gypi
index 15ead282dc67bc51f0c57bc82315481959d1670f..462fb4ca7eb3c1031e23db9a9a44ebc98e8648cf 100644
--- a/build/grit_action.gypi
+++ b/build/grit_action.gypi
@@ -21,6 +21,7 @@
     # instead of build/common.gypi .
     'grit_additional_defines%': [],
     'grit_rc_header_format%': [],
+    'grit_whitelist%': '',
 
     'conditions': [
       # These scripts can skip writing generated files if they are identical
@@ -36,6 +37,17 @@
       }],
     ],
   },
+  'conditions': [
+    ['"<(grit_whitelist)"==""', {
+      'variables': {
+        'grit_whitelist_flag': [],
+      }
+    }, {
+      'variables': {
+        'grit_whitelist_flag': ['-w', '<(grit_whitelist)'],
+      }
+    }]
+  ],
   'inputs': [
     '<!@pymod_do_main(grit_info <@(grit_defines) <@(grit_additional_defines) '
         '--inputs <(grit_grd_file) -f "<(grit_resource_ids)")',
@@ -51,6 +63,7 @@
              '-o', '<(grit_out_dir)',
              '--write-only-new=<(write_only_new)',
              '<@(grit_defines)',
+             '<@(grit_whitelist_flag)',
              '<@(grit_additional_defines)',
              '<@(grit_rc_header_format)'],
   'message': 'Generating resources from <(grit_grd_file)',