Attempt 3 at:

content/content_tests.gypi

Index: content/content_tests.gypi
diff --git a/content/content_tests.gypi b/content/content_tests.gypi
index 60c76263cdaa83d26b1be8a033bcc75c51073583..38e858d03d3d907c4a89e18a7238eaace13c7c39 100644
--- a/content/content_tests.gypi
+++ b/content/content_tests.gypi
@@ -21,7 +21,6 @@
         '../third_party/webrtc/system_wrappers/source/system_wrappers.gyp:system_wrappers',
         '../third_party/webrtc/video_engine/video_engine.gyp:video_engine_core',
         '../third_party/webrtc/voice_engine/voice_engine.gyp:voice_engine_core',
-        '../ui/gfx/compositor/compositor.gyp:test_compositor',
         '../ui/gfx/surface/surface.gyp:surface',
         '../ui/ui.gyp:ui_test_support',
         '../webkit/support/webkit_support.gyp:appcache',
@@ -121,6 +120,15 @@
             '../build/linux/system.gyp:glib',
           ],
         }],
+        ['use_webkit_compositor==1', {
+          'dependencies': [
+            '../ui/gfx/compositor/compositor.gyp:compositor',
+          ],
+        }, {
+          'dependencies': [
+            '../ui/gfx/compositor/compositor.gyp:test_compositor',
+          ],
+        }],
       ],
     },
     {