GN: Build rules and fixes for (almost) all mojo unittest targets

mojo/mojo_services.gypi

 # Copyright (c) 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.
 
 {
   'targets': [
     {
       # GN version: //mojo/services/dbus_echo:bindings
       'target_name': 'mojo_echo_bindings',
       'type': 'static_library',
@@ skipping 157 matching lines @@
       'export_dependent_settings': [
         'mojo_geometry_lib',
       ],
       'sources': [
         'services/public/cpp/surfaces/lib/surfaces_type_converters.cc',
         'services/public/cpp/surfaces/surfaces_type_converters.h',
         'services/public/cpp/surfaces/mojo_surfaces_export.h',
       ],
     },
     {
+      # GN version: //mojo/services/public/cpp/surfaces/tests
       'target_name': 'mojo_surfaces_lib_unittests',
       'type': 'executable',
       'dependencies': [
         '../base/base.gyp:base',
         '../base/base.gyp:test_support_base',
         '../cc/cc.gyp:cc',
         '../cc/cc.gyp:cc_surfaces',
         '../gpu/gpu.gyp:gpu',
         '../skia/skia.gyp:skia',
         '../testing/gtest.gyp:gtest',
@@ skipping 702 matching lines @@
             'mojo_echo_bindings',
           ],
           'sources': [
             'services/dbus_echo/dbus_echo_service.cc',
           ],
         },
       ],
     }],
   ],
 }