linux_aura: Use the linux assets for the window caption buttons.

Previously, we were using the windows assets. As is, this is functional,
but will require further patches to get the button spacing correct.

BUG=281788

Review URL: https://chromiumcodereview.appspot.com/23993003

git-svn-id: http://src.chromium.org/svn/trunk/src/build@221875 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -143,6 +143,13 @@
             'toolkit_uses_gtk%': 0,
           }],
 
+          # Whether we're a traditional desktop unix.
+          ['(OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris") and chromeos==0', {
+            'desktop_linux%': 1,
+          }, {
+            'desktop_linux%': 0,
+          }],
+
           # Enable HiDPI on Mac OS and Chrome OS.
           ['OS=="mac" or chromeos==1', {
             'enable_hidpi%': 1,
@@ -174,6 +181,7 @@
       'target_arch%': '<(target_arch)',
       'toolkit_views%': '<(toolkit_views)',
       'toolkit_uses_gtk%': '<(toolkit_uses_gtk)',
+      'desktop_linux%': '<(desktop_linux)',
       'use_aura%': '<(use_aura)',
       'use_ash%': '<(use_ash)',
       'use_cras%': '<(use_cras)',
@@ -803,6 +811,7 @@
     'use_pango%': '<(use_pango)',
     'use_ozone%': '<(use_ozone)',
     'toolkit_uses_gtk%': '<(toolkit_uses_gtk)',
+    'desktop_linux%': '<(desktop_linux)',
     'use_x11%': '<(use_x11)',
     'use_gnome_keyring%': '<(use_gnome_keyring)',
     'linux_fpic%': '<(linux_fpic)',
@@ -1545,6 +1554,9 @@
       ['chromeos==1', {
         'grit_defines': ['-D', 'chromeos', '-D', 'scale_factors=2x'],
       }],
+      ['desktop_linux==1', {
+        'grit_defines': ['-D', 'desktop_linux'],
+      }],
       ['toolkit_views==1', {
         'grit_defines': ['-D', 'toolkit_views'],
       }],