Revert of [mojo-bindings] Use Watch API instead of MessagePumpMojo

mojo/mojo_edk_tests.gyp

 # Copyright 2015 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.
 
 {
   'includes': [
     'mojo_variables.gypi',
   ],
   'targets': [
     {
@@ skipping 132 matching lines @@
       ],
     },
     {
       # GN version: //mojo/public/cpp/system/tests:mojo_public_system_unittests
       # and         //mojo/public/c/system/tests
       'target_name': 'mojo_public_system_unittests',
       'type': 'executable',
       'dependencies': [
         '../testing/gtest.gyp:gtest',
         'mojo_edk.gyp:mojo_run_all_unittests',
-        'mojo_public.gyp:mojo_cpp_system',
         'mojo_public.gyp:mojo_public_test_utils',
       ],
       'sources': [
         '<@(mojo_public_system_unittest_sources)',
       ],
     },
     {
       # GN version: //mojo/public/cpp/application/tests:mojo_public_utility_unittests
       'target_name': 'mojo_public_utility_unittests',
       'type': 'executable',
@@ skipping 195 matching lines @@
             '../build/isolate.gypi',
           ],
           'sources': [
             'mojo_public_utility_unittests.isolate',
           ],
         },
       ],
     }],
   ],
 }