Fix Aura build when toolkit_views==0

ui/base/ui_base.gyp

Index: ui/base/ui_base.gyp
diff --git a/ui/base/ui_base.gyp b/ui/base/ui_base.gyp
index 21090e469ffba497e61f297ebcef3e644ada50f6..b1b7168479a5cc9af45f750620ceab655781efcd 100644
--- a/ui/base/ui_base.gyp
+++ b/ui/base/ui_base.gyp
@@ -389,6 +389,13 @@
                 ['exclude', '^dragdrop/drag_utils.cc'],
                 ['exclude', '^dragdrop/drag_utils.h'],
               ],
+            }, {
+              'sources/': [
+                ['include', '^dragdrop/os_exchange_data.cc'],
+                ['include', '^dragdrop/os_exchange_data.h'],
+                ['include', '^nine_image_painter_factory.cc'],
+                ['include', '^nine_image_painter_factory.h'],
+              ],
             }],
           ],
         }],