Add a mojoPrivate API that exposes mojo to component apps/extensions.

extensions/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("//tools/grit/grit_rule.gni")
 import("//tools/grit/repack.gni")
 
 assert(enable_extensions)
 
 # GYP version: extensions/extensions_resources.gyp:extensions_resources
@@ skipping 217 matching lines @@
       "common/manifest_handlers/oauth2_manifest_unittest.cc",
       "common/manifest_handlers/shared_module_manifest_unittest.cc",
       "common/message_bundle_unittest.cc",
       "common/one_shot_event_unittest.cc",
       "common/permissions/manifest_permission_set_unittest.cc",
       "common/stack_frame_unittest.cc",
       "common/url_pattern_set_unittest.cc",
       "common/url_pattern_unittest.cc",
       "common/user_script_unittest.cc",
       "renderer/activity_log_converter_strategy_unittest.cc",
+      "renderer/api/mojo_private/mojo_private_unittest.cc",
       "renderer/api/serial/data_receiver_unittest.cc",
       "renderer/api/serial/data_sender_unittest.cc",
       "renderer/api/serial/serial_api_unittest.cc",
       "renderer/api_test_base.cc",
       "renderer/api_test_base.h",
       "renderer/api_test_base_unittest.cc",
       "renderer/event_unittest.cc",
       "renderer/json_schema_unittest.cc",
       "renderer/messaging_utils_unittest.cc",
       "renderer/module_system_test.cc",
@@ skipping 27 matching lines @@
       "//testing/gmock",
       "//testing/gtest",
       "//third_party/leveldatabase",
     ]
 
     if (is_win) {
       deps += [ "//base/allocator" ]
     }
   }
 }