Make use_nss a gyp var so that aura can build w/ nss.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index 17d707f8a383fe493bab72c7902953cf5e6d2479..bd0a7b3b7401b40ec16d44ebeb3c52e29a272f7e 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -86,6 +86,11 @@
           ['use_aura==1 or touchui==1', {
             'views_compositor%': 1,
           }],
+          ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris"', {
+            'use_nss%': 1,

[mattm, 2011/10/05 03:44:47]

Did you see the question about whether these could go in one of the other
less-nested condition blocks?

[DaveMoore, 2011/10/05 04:02:57]

Done.

+          }, {
+            'use_nss%': 0,
+          }],
         ],
       },
 
@@ -98,6 +103,7 @@
       'use_only_pure_views%': '<(use_only_pure_views)',
       'views_compositor%': '<(views_compositor)',
       'use_aura%': '<(use_aura)',
+      'use_nss%': '<(use_nss)',
 
       # We used to provide a variable for changing how libraries were built.
       # This variable remains until we can clean up all the users.
@@ -328,6 +334,7 @@
     'use_only_pure_views%': '<(use_only_pure_views)',
     'views_compositor%': '<(views_compositor)',
     'use_aura%': '<(use_aura)',
+    'use_nss%': '<(use_nss)',
     'os_posix%': '<(os_posix)',
     'use_glib%': '<(use_glib)',
     'toolkit_uses_gtk%': '<(toolkit_uses_gtk)',
@@ -770,6 +777,9 @@
       ['use_aura==1', {
         'grit_defines': ['-D', 'use_aura'],
       }],
+      ['use_nss==1', {
+        'grit_defines': ['-D', 'use_nss'],
+      }],
       ['touchui==1', {
         'grit_defines': ['-D', 'touchui'],
       }],
@@ -904,6 +914,9 @@
       ['use_aura==1', {
         'defines': ['USE_AURA=1'],
       }],
+      ['use_nss==1', {
+        'defines': ['USE_NSS=1'],
+      }],
       ['toolkit_uses_gtk==1', {
         'defines': ['TOOLKIT_USES_GTK=1'],
       }],