Move Ash wallpapers into a separate grd/pak file to avoid duplication

ui/ui_resources.gypi

Index: ui/ui_resources.gypi
diff --git a/ui/ui_resources.gypi b/ui/ui_resources.gypi
index a872ec86eaa210ce99cc62f10edafd89bbc9920c..8dc9d43da9f1920c9e236e81dbaf6544acd8d43d 100644
--- a/ui/ui_resources.gypi
+++ b/ui/ui_resources.gypi
@@ -31,5 +31,26 @@
       ],
       'includes': [ '../build/grit_target.gypi' ],
     },
+    {
+      'target_name': 'ui_resources_wallpapers',
+      'type': 'none',
+      'conditions': [
+        ['use_ash==1', {
+          'variables': {
+            'grit_out_dir': '<(SHARED_INTERMEDIATE_DIR)/ui/ui_resources',
+          },
+          'actions': [
+            {
+              'action_name': 'ui_resources_wallpapers',
+              'variables': {
+                'grit_grd_file': 'resources/ui_resources_wallpapers.grd',
+              },
+              'includes': [ '../build/grit_action.gypi' ],
+            },
+          ],
+          'includes': [ '../build/grit_target.gypi' ],
+        }],
+      ],
+    },
   ],
 }