Add GN buildfiles for ui/compositor and snapshot.

ui/ozone/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//ui/ozone/ozone.gni")
 
 declare_args() {
   # The default platform for Ozone.
   ozone_platform = "test"
 }
@@ skipping 13 matching lines @@
     "ozone_switches.cc",
     "ozone_switches.h",
   ]
 
   defines = [ "OZONE_IMPLEMENTATION" ]
 
   deps = [
     ":generate_ozone_platform_list",
     "//base",
     "//skia",
-    "//ui/base:ui_base",
+    "//ui/base",
     "//ui/events",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//ui/gfx/ozone",
   ]
 }
 
 # TODO(GYP) implement the ozone platforms. This should check the various
 # ozone_platform_*flags, and add deps and add to the ozone_platforms list for
 # the script below.
 ozone_platforms = ""
 
 action("generate_ozone_platform_list") {
   script = "generate_ozone_platform_list.py"
   outputs = [ platform_list_file ]
 
   args = [
     "--output_file=" + rebase_path(platform_list_file, root_build_dir),
     "--default=$ozone_platform",
     ozone_platforms,
   ]
 }