GN: Make content_shell and webkit_unit_tests work in component build

ipc/mojo/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.
 
 component("mojo") {
   sources = [
     "ipc_channel_mojo.cc",
     "ipc_channel_mojo.h",
     "ipc_message_pipe_reader.cc",
     "ipc_message_pipe_reader.h",
   ]
 
+  defines = [ "IPC_MOJO_IMPLEMENTATION" ]
+
   deps = [
     "//base",
+    "//base/third_party/dynamic_annotations",
     "//ipc",
+    "//mojo/environment:chromium",
     "//mojo/public/cpp/bindings",
     "//mojo/system",
-    # TODO(viettrungluu): Needed for base/lazy_instance.h, which is suspect.
-    "//base/third_party/dynamic_annotations",
   ]
 }
 
 test("ipc_mojo_unittests") {
   sources = [
     "ipc_channel_mojo_unittest.cc",
     "run_all_unittests.cc",
   ]
 
   deps = [
     "//base",
-    # TODO(viettrungluu): Needed for base/lazy_instance.h, which is suspect.
     "//base/test:test_support",
     "//base/third_party/dynamic_annotations",
     "//ipc",
     "//ipc:test_support",
     "//ipc/mojo",
     "//mojo/environment:chromium",
     "//mojo/system",
     "//url",
   ]
 }