Remove mojo/tools/, not needed in chromium

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.
 
 import("//build/config/ui.gni")
 
 group("mojo") {
   # Meta-target, don't link into production code.
   testonly = true
   deps = [
     ":tests",
     "//mojo/common",
     "//mojo/public",
     "//mojo/services",
-    "//mojo/tools/package_manager",
   ]
 
   if (is_android) {
     deps += [
       "//mojo/android",
     ]
   }
 }
 
 group("tests") {
   testonly = true
   deps = [
     "//mojo/application_manager:mojo_application_manager_unittests",
     "//mojo/bindings/js/tests:mojo_js_unittests",
     "//mojo/common:mojo_common_unittests",
     "//mojo/converters/surfaces/tests:mojo_surfaces_lib_unittests",
     "//mojo/edk/system:mojo_message_pipe_perftests",
     "//mojo/edk/system:mojo_system_unittests",
     "//mojo/public/c/system/tests:perftests",
     "//mojo/public/cpp/application/tests:mojo_public_application_unittests",
     "//mojo/public/cpp/bindings/tests:mojo_public_bindings_unittests",
     "//mojo/public/cpp/environment/tests:mojo_public_environment_unittests",
     "//mojo/public/cpp/system/tests:mojo_public_system_unittests",
     "//mojo/public/cpp/utility/tests:mojo_public_utility_unittests",
-    "//mojo/tools:message_generator",
   ]
 }