Add BeginFrameObserverProxy

ui/compositor/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("//build/config/ui.gni")
 import("//testing/test.gni")
 
 component("compositor") {
   sources = [
     "closure_animation_observer.cc",
@@ skipping 126 matching lines @@
   if (use_ozone) {
     sources += [ "test/test_compositor_host_ozone.cc" ]
   } else if (use_x11) {
     sources += [ "test/test_compositor_host_x11.cc" ]
   }
 }
 
 if (!is_android) {
   test("compositor_unittests") {
     sources = [
+      "compositor_unittest.cc",
       "layer_animation_element_unittest.cc",
       "layer_animation_sequence_unittest.cc",
       "layer_animator_unittest.cc",
       "layer_owner_unittest.cc",
       "layer_unittest.cc",
       "run_all_unittests.cc",
       "transform_animation_curve_adapter_unittest.cc",
     ]
 
     deps = [
@@ skipping 11 matching lines @@
       "//ui/gfx/geometry",
       "//ui/gl",
       "//ui/resources",
     ]
 
     if (is_linux) {
       deps += [ "//third_party/mesa:osmesa" ]
     }
   }
 }