Fix chrome build inside the Chromium OS build chroot.

In the chroot used for building Chromium OS, gnome-keyring
is not installed so the gyp fails with the errors like:

Exception: Call to 'pkg-config --cflags gnome-keyring-1' returned exit status 1. while loading dependencies of src/base/base.gyp while loading dependencies of src/net/net.gyp while loading dependencies of src/app/app.gyp while loading dependencies of src/build/all.gyp while trying to load src/build/all.gyp
failed to run command: /usr/bin/python src/build/gyp_chromium

BUG=chromium-os:4000
TEST=Tested on Ubuntu and in the chroot:
On Ubuntu:
  % sudo apt-get remove libgnome-keyring-dev
  % GYP_DEFINES="chromeos=0" gclient runhooks'
  ... gyp fails as libgnome-keyring-dev is not installed ...
  % GYP_DEFINES="chromeos=1" gclient runhooks'
  ... gyp succeeds ...

In the chromium os build chroot:
  % emerge-x86-generic chromeos-chrome
  ... gyp suceeds ...

Review URL: http://codereview.chromium.org/2729010

git-svn-id: http://src.chromium.org/svn/trunk/src/build@49373 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

linux/system.gyp

@@ -258,32 +258,36 @@
     {
       'target_name': 'gnome-keyring',
       'type': 'settings',
-      'direct_dependent_settings': {
-        'cflags': [
-          '<!@(<(pkg-config) --cflags gnome-keyring-1)',
-        ],
-        'conditions': [
-          ['linux_link_gnome_keyring==0', {
-            'defines': ['DLOPEN_GNOME_KEYRING'],
-          }],
-        ],
-      },
       'conditions': [
-        ['linux_link_gnome_keyring!=0', {
-          'link_settings': {
-            'ldflags': [
-              '<!@(<(pkg-config) --libs-only-L --libs-only-other gnome-keyring-1)',
+        ['chromeos==0', {
+          'direct_dependent_settings': {
+            'cflags': [
+              '<!@(<(pkg-config) --cflags gnome-keyring-1)',
             ],
-            'libraries': [
-              '<!@(<(pkg-config) --libs-only-l gnome-keyring-1)',
-            ],
-          },
-        }, {
-          'link_settings': {
-            'libraries': [
-              '-ldl',
+            'conditions': [
+              ['linux_link_gnome_keyring==0', {
+                'defines': ['DLOPEN_GNOME_KEYRING'],
+              }],
             ],
           },
+          'conditions': [
+            ['linux_link_gnome_keyring!=0', {
+              'link_settings': {
+                'ldflags': [
+                  '<!@(<(pkg-config) --libs-only-L --libs-only-other gnome-keyring-1)',
+                ],
+                'libraries': [
+                  '<!@(<(pkg-config) --libs-only-l gnome-keyring-1)',
+                ],
+              },
+            }, {
+              'link_settings': {
+                'libraries': [
+                  '-ldl',
+                ],
+              },
+            }],
+          ],
         }],
       ],
     },