Attempt 3 at:

ui/aura/aura.gyp

Index: ui/aura/aura.gyp
diff --git a/ui/aura/aura.gyp b/ui/aura/aura.gyp
index 735f067b65509de91955d02309a871c500d8f971..f6e03a67ecfe1a1ba70dfb4ba5dfa5f72b6b390e 100644
--- a/ui/aura/aura.gyp
+++ b/ui/aura/aura.gyp
@@ -60,7 +60,6 @@
       'dependencies': [
         '../../skia/skia.gyp:skia',
         '../../testing/gtest.gyp:gtest',
-        '../gfx/compositor/compositor.gyp:test_compositor',
         '../ui.gyp:ui',
         'aura',
       ],
@@ -81,6 +80,13 @@
         'test/test_window_delegate.cc',
         'test/test_window_delegate.h',
       ],
+      'conditions': [
+        ['use_webkit_compositor==0', {
+          'dependencies': [
+            '../gfx/compositor/compositor.gyp:test_compositor',
+          ],
+        }],
+      ],
     },
     {
       'target_name': 'aura_demo',
@@ -116,7 +122,6 @@
         '../../skia/skia.gyp:skia',
         '../../testing/gtest.gyp:gtest',
         '../gfx/compositor/compositor.gyp:compositor_test_support',
-        '../gfx/compositor/compositor.gyp:test_compositor',
         '../gfx/gl/gl.gyp:gl',
         '../ui.gyp:gfx_resources',
         '../ui.gyp:ui',
@@ -144,6 +149,15 @@
             '<(DEPTH)/third_party/mesa/mesa.gyp:osmesa',
           ],
         }],
+        ['use_webkit_compositor==1', {
+          'dependencies': [
+            '../gfx/compositor/compositor.gyp:compositor',
+          ],
+        }, { # use_webkit_compositor!=1
+          'dependencies': [
+            '../gfx/compositor/compositor.gyp:test_compositor',
+          ],
+        }],
       ],
     },
   ],