Change mojo application name to {name}.mojo

examples/sample_app/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.
 
-shared_library("sample_app") {
+import("//mojo/public/mojo_application.gni")
+
+mojo_native_application("sample_app") {
   sources = [
     "gles2_client_impl.cc",
     "gles2_client_impl.h",
     "sample_app.cc",
   ]
 
   deps = [
     ":spinning_cube",
     "//base",
     "//gpu/command_buffer/client:gles2_interface",
@@ skipping 11 matching lines @@
   sources = [
     "spinning_cube.cc",
     "spinning_cube.h"
   ]
 
   deps = [
     "//base",
     "//mojo/public/gles2:for_shared_library",
   ]
 }