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

build/common.gypi

 # Copyright (c) 2011 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 233 matching lines @@
           'use_skia%': 1,
         }],
 
         # A flag for POSIX platforms
         ['OS=="win"', {
           'os_posix%': 0,
         }, {
           'os_posix%': 1,
         }],
 
+        # NSS usage.
+        ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris"', {
+          'use_nss%': 1,
+        }, {
+          'use_nss%': 0,
+        }],
+        
         # Flags to use X11 on non-Mac POSIX platforms
         ['OS=="win" or OS=="mac" or OS=="android"', {
           'use_glib%': 0,
           'toolkit_uses_gtk%': 0,
           'use_x11%': 0,
         }, {
           # TODO(dnicoara) Wayland build should have these disabled, but
           # currently GTK and X is too spread and it's hard to completely
           # remove every dependency.
           'use_glib%': 1,
@@ skipping 57 matching lines @@
     # Copy conditionally-set variables out one scope.
     'branding%': '<(branding)',
     'buildtype%': '<(buildtype)',
     'target_arch%': '<(target_arch)',
     'host_arch%': '<(host_arch)',
     'library%': 'static_library',
     'toolkit_views%': '<(toolkit_views)',
     '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)',
     'use_skia%': '<(use_skia)',
     'use_x11%': '<(use_x11)',
     'use_gnome_keyring%': '<(use_gnome_keyring)',
     'linux_fpic%': '<(linux_fpic)',
     'enable_flapper_hacks%': '<(enable_flapper_hacks)',
     'chromeos%': '<(chromeos)',
     'touchui%': '<(touchui)',
@@ skipping 422 matching lines @@
       }],
       ['toolkit_views==1', {
         'grit_defines': ['-D', 'toolkit_views'],
       }],
       ['use_only_pure_views==1', {
         'grit_defines': ['-D', 'use_only_pure_views'],
       }],
       ['use_aura==1', {
         'grit_defines': ['-D', 'use_aura'],
       }],
+      ['use_nss==1', {
+        'grit_defines': ['-D', 'use_nss'],
+      }],
       ['touchui==1', {
         'grit_defines': ['-D', 'touchui'],
       }],
       ['use_virtual_keyboard==1', {
         'grit_defines': ['-D', 'use_virtual_keyboard'],
       }],
       ['file_manager_extension==1', {
         'grit_defines': ['-D', 'file_manager_extension'],
       }],
       ['webui_task_manager==1', {
@@ skipping 114 matching lines @@
       }],
       ['use_only_pure_views==1', {
         'defines': ['USE_ONLY_PURE_VIEWS=1'],
       }],
       ['views_compositor==1', {
         'defines': ['VIEWS_COMPOSITOR=1'],
       }],
       ['use_aura==1', {
         'defines': ['USE_AURA=1'],
       }],
+      ['use_nss==1', {
+        'defines': ['USE_NSS=1'],
+      }],
       ['toolkit_uses_gtk==1', {
         'defines': ['TOOLKIT_USES_GTK=1'],
       }],
       ['chromeos==1', {
         'defines': ['OS_CHROMEOS=1'],
       }],
       ['touchui==1', {
         'defines': ['TOUCH_UI=1'],
       }],
       ['use_virtual_keyboard==1', {
@@ skipping 1561 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }