Add fake implementation of Surfaces service for sky tests

sky/tools/webkitpy/layout_tests/port/base.py

Index: sky/tools/webkitpy/layout_tests/port/base.py
diff --git a/sky/tools/webkitpy/layout_tests/port/base.py b/sky/tools/webkitpy/layout_tests/port/base.py
index efcfa6f78f20682280759d98a9baac18b0c02bf6..c2e33aab694794cdddfdd0d57561c49c02ce5f79 100644
--- a/sky/tools/webkitpy/layout_tests/port/base.py
+++ b/sky/tools/webkitpy/layout_tests/port/base.py
@@ -230,7 +230,7 @@ class Port(object):
             return [
                 '--args-for=mojo:native_viewport_service --use-headless-config --use-osmesa',
                 '--content-handlers=text/sky,mojo:sky_viewer',
-                '--url-mappings=mojo:window_manager=mojo:sky_tester',
+                '--url-mappings=mojo:window_manager=mojo:sky_tester,mojo:surfaces_service=mojo:fake_surfaces_service',
                 'mojo:window_manager',
             ]
         return []