Cleanup GN BUILD files, gni's and imports.

components/view_manager/public/cpp/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/module_args/mojo.gni")
 import("//third_party/mojo/src/mojo/public/mojo_sdk.gni")
 
 mojo_sdk_source_set("cpp") {
   restrict_external_deps = false
   sources = [
     "args.h",
     "lib/args.cc",
     "lib/view.cc",
     "lib/view_manager_client_factory.cc",
     "lib/view_manager_client_impl.cc",
@@ skipping 35 matching lines @@
 }
 
 source_set("common") {
   sources = [
     "keys.cc",
     "keys.h",
     "types.h",
     "util.h",
   ]
 }