Always use webkit compositor

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index c2cc6d498a12dae04fab351e6540b264708aa84e..c1bdb624953344d422f3391060c24ede3ab38dad 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -83,13 +83,6 @@
           ['use_aura==1', {
             'views_compositor%': 1,
           }],
-
-          # Use the WebKit compositor for ui, when Aura is on.
-          ['use_aura==1', {
-            'use_webkit_compositor%': 1,
-          }, {
-            'use_webkit_compositor%': 0,
-          }],
         ],
       },
 
@@ -98,7 +91,6 @@
       'host_arch%': '<(host_arch)',
       'toolkit_views%': '<(toolkit_views)',
       'views_compositor%': '<(views_compositor)',
-      'use_webkit_compositor%': '<(use_webkit_compositor)',
       'use_aura%': '<(use_aura)',
       'use_ash%': '<(use_ash)',
       'use_openssl%': '<(use_openssl)',
@@ -261,6 +253,9 @@
       # Enable plug-in installation by default.
       'enable_plugin_installation%': 1,
 
+      # Use the WebKit compositor for ui.
+      'use_webkit_compositor%': 1,
+
       'conditions': [
         # TODO(epoger): Figure out how to set use_skia=1 for Mac outside of
         # the 'conditions' clause.  Initial attempts resulted in chromium and