Revert of Move gn _run target generation into test().

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 = [
     "callback_layer_animation_observer.cc",
@@ skipping 142 matching lines @@
     deps += [ "//ui/gfx/x" ]
   }
 
   if (use_ozone) {
     sources += [ "test/test_compositor_host_ozone.cc" ]
   } else if (use_x11) {
     sources += [ "test/test_compositor_host_x11.cc" ]
   }
 }
 
+# TODO(GYP): Delete this after we've converted everything to GN.
+# The _run targets exist only for compatibility w/ GYP.
+group("compositor_unittests_run") {
+  testonly = true
+  deps = [
+    ":compositor_unittests",
+  ]
+}
+
 test("compositor_unittests") {
   sources = [
     "callback_layer_animation_observer_unittest.cc",
     "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",
@@ skipping 17 matching lines @@
     "//ui/base",
     "//ui/gfx",
     "//ui/gfx/geometry",
     "//ui/gl",
     "//ui/resources",
   ]
   if (is_linux) {
     deps += [ "//third_party/mesa:osmesa" ]
   }
 }