Add file system service to Dart's embedder private package

BUG=
R=zra@google.com

Review URL: https://codereview.chromium.org/1531293002 .

mojo/dart/embedder/BUILD.gn

diff --git a/mojo/dart/embedder/BUILD.gn b/mojo/dart/embedder/BUILD.gn
index b933f1b..a42b19d 100644
--- a/mojo/dart/embedder/BUILD.gn
+++ b/mojo/dart/embedder/BUILD.gn
@@ -75,6 +75,7 @@
     ":dart_embedder_package_bindings",
     ":dart_embedder_package_network",
     ":dart_embedder_package_network_service",
+    ":dart_embedder_package_files_service",
   ]
 }
 
@@ -98,6 +99,11 @@
   destination = "mojo_services/mojo"
 }
 
+dart_embedder_package("dart_embedder_package_files_service") {
+  package = "mojo/services/files/interfaces"
+  destination = "mojo_services/mojo/files"
+}
+
 action_foreach("dart_embedder_package_sdk") {
   sources = rebase_path(package_mojo_sources + dart_mojo_internal_sdk_sources,
                         "",
@@ -168,6 +174,7 @@
   bindings_mojoms = rebase_path("//mojo/public/interfaces/bindings")
   network_mojoms = rebase_path("//mojo/public/interfaces/network")
   network_service_mojoms = rebase_path("//mojo/services/network/interfaces")
+  files_mojoms = rebase_path("//mojo/services/files/interfaces")
 
   # This script generates --url_mapping command line arguments for all
   # generated mojom.dart bindings files. See HACKING.md for more information.
@@ -182,6 +189,7 @@
                     "$bindings_mojoms,mojo/mojo",
                     "$network_mojoms,mojo/mojo",
                     "$network_service_mojoms,mojo_services/mojo",
+                    "$files_mojoms,mojo_services/mojo/files",
                   ],
                   "list lines")
 

mojo/dart/embedder/packages.dart

diff --git a/mojo/dart/embedder/packages.dart b/mojo/dart/embedder/packages.dart
index ef815bd..8f40025 100644
--- a/mojo/dart/embedder/packages.dart
+++ b/mojo/dart/embedder/packages.dart
@@ -15,9 +15,11 @@
 
 // DO NOT export anything from this library.
 
+// Core packages.
 import 'dart:_mojo/application.dart';
 import 'dart:_mojo/bindings.dart';
 import 'dart:_mojo/core.dart';
+// Network.
 import 'dart:_mojo/mojo/network_error.mojom.dart';
 import 'dart:_mojo_services/mojo/host_resolver.mojom.dart';
 import 'dart:_mojo_services/mojo/net_address.mojom.dart';
@@ -25,3 +27,9 @@
 import 'dart:_mojo_services/mojo/tcp_bound_socket.mojom.dart';
 import 'dart:_mojo_services/mojo/tcp_connected_socket.mojom.dart';
 import 'dart:_mojo_services/mojo/tcp_server_socket.mojom.dart';
+// File system.
+import 'dart:_mojo_services/mojo/files/file.mojom.dart';
+import 'dart:_mojo_services/mojo/files/files.mojom.dart';
+import 'dart:_mojo_services/mojo/files/directory.mojom.dart';
+import 'dart:_mojo_services/mojo/files/ioctl.mojom.dart';
+import 'dart:_mojo_services/mojo/files/types.mojom.dart';
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