[Reland] Mojo: Eliminate duplicate C API symbols

mojo/mojo_edk.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',
-  ],
+  'variables': {
+    'chromium_code': 1,
+  },
   'target_defaults' : {
     'include_dirs': [
       '..',
     ],
     'direct_dependent_settings': {
       'include_dirs': [
         '..',
       ],
     },
   },
@@ skipping 28 matching lines @@
       ],
     },
     {
       # GN version: //mojo/edk/system
       'target_name': 'mojo_system_impl',
       'type': '<(component)',
       'dependencies': [
         '../base/base.gyp:base',
         '../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
         '../crypto/crypto.gyp:crypto',
-        'mojo_public.gyp:mojo_system_headers',
+        'mojo_public.gyp:mojo_public_system',
         'mojo_system_ports',
       ],
       'defines': [
         'MOJO_SYSTEM_IMPL_IMPLEMENTATION',
-        'MOJO_SYSTEM_IMPLEMENTATION',
-        'MOJO_USE_SYSTEM_IMPL',
       ],
       'sources': [
         'edk/embedder/configuration.h',
         'edk/embedder/embedder.cc',
         'edk/embedder/embedder.h',
         'edk/embedder/embedder_internal.h',
         'edk/embedder/entrypoints.cc',
         'edk/embedder/named_platform_channel_pair_win.cc',
         'edk/embedder/named_platform_channel_pair_win.h',
         'edk/embedder/platform_channel_pair.cc',
@@ skipping 67 matching lines @@
         'edk/system/watcher.h',
         'edk/system/watcher_set.cc',
         'edk/system/watcher_set.h',
         # Test-only code:
         # TODO(vtl): It's a little unfortunate that these end up in the same
         # component as non-test-only code. In the static build, this code
         # should hopefully be dead-stripped.
         'edk/embedder/test_embedder.cc',
         'edk/embedder/test_embedder.h',
       ],
-      'all_dependent_settings': {
-        # Ensures that dependent projects import the core functions on Windows.
-        'defines': ['MOJO_USE_SYSTEM_IMPL'],
-      },
       'conditions': [
         ['OS=="android"', {
           'dependencies': [
             '../third_party/ashmem/ashmem.gyp:ashmem',
           ],
         }],
         ['OS=="win"', {
            # Structure was padded due to __declspec(align()), which is
            # uninteresting.
           'msvs_disabled_warnings': [ 4324 ],
@@ skipping 108 matching lines @@
         'mojo_public.gyp:mojo_public_test_support',
         'mojo_system_impl',
         'mojo_test_support_impl',
       ],
       'sources': [
         'edk/test/run_all_perftests.cc',
       ],
     },
   ],
 }