Get mojo_shell building inside chromium checkout.

third_party/mojo/src/mojo/public/tools/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("../mojo.gni")
 
-if (mojo_use_prebuilt_mojo_shell) {
-  copy("copy_mojo_shell") {
-    filename = "mojo_shell"
-    if (is_android) {
-      filename = "MojoShell.apk"
-      sources = [
-        "prebuilt/shell/android-arm/$filename",
-      ]
-      outputs = [
-        "$root_out_dir/apks/$filename",
-      ]
-    } else {
-      assert(is_linux)
-      sources = [
-        "prebuilt/shell/linux-x64/$filename",
-      ]
-      outputs = [
-        "$root_out_dir/$filename",
-      ]
-    }
-  }
-}
-
 if (mojo_use_prebuilt_network_service) {
   copy("copy_network_service") {
     filename = "network_service.mojo"
     if (defined(mojo_prebuilt_network_service_location) &&
         mojo_prebuilt_network_service_location != "") {
       sources = [
         "$mojo_prebuilt_network_service_location",
       ]
     } else {
       if (is_android) {
@@ skipping 40 matching lines @@
 if (mojo_use_dart_apptest_framework) {
   copy("dart_apptest_framework") {
     sources = [
       "prebuilt/frameworks/apptest.dartzip",
     ]
     outputs = [
       "$target_out_dir/dart_apptest_framework.dartzip",
     ]
   }
 }