Fix a TODO in GN file

mash/session/BUILD.gn

 # Copyright 2015 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")
 import("//services/service_manager/public/cpp/service.gni")
 import("//services/service_manager/public/service_manifest.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//tools/grit/repack.gni")
 
 source_set("lib") {
   sources = [
     "session.cc",
     "session.h",
   ]
 
   deps = [
     "//base",
     "//content/public/common:service_names",
     "//mash/common",
     "//mash/quick_launch/public/interfaces:constants",
     "//mojo/common",
     "//mojo/public/cpp/bindings",
     "//services/service_manager/public/cpp",
-    "//services/service_manager/public/cpp:sources",
+    "//services/service_manager/public/cpp",
   ]
 
   data_deps = [
     "//mash/quick_launch",
   ]
 
   if (is_chromeos) {
     data_deps += [ "//ash/mus" ]
   }
 }
 
 service("session") {
   output_name = "mash_session"
 
   sources = [
     "main.cc",
   ]
 
   deps = [
     ":lib",
     "//base",
     "//mojo/common",
     "//mojo/public/cpp/bindings",
     "//services/service_manager/public/cpp",
-    "//services/service_manager/public/cpp:sources",
+    "//services/service_manager/public/cpp",
   ]
 }
 
 service_manifest("manifest") {
   name = "mash_session"
   source = "manifest.json"
 }