Refactors keyboard related code so mash can use a keyboard

ash/mus/BUILD.gn

Index: ash/mus/BUILD.gn
diff --git a/ash/mus/BUILD.gn b/ash/mus/BUILD.gn
index 11b4527c2e5906159969f0e6b22e4551c6a0f411..678cfd73caf56bb40b81f12846cd2e95bfdf8a8f 100644
--- a/ash/mus/BUILD.gn
+++ b/ash/mus/BUILD.gn
@@ -9,6 +9,9 @@ import("//tools/grit/repack.gni")
 
 source_set("lib") {
   sources = [
+    "keyboard_ui_mus.cc",
+    "keyboard_ui_mus.h",
+    "mojo_shell.h",
     "shell_delegate_mus.cc",
     "shell_delegate_mus.h",
     "stub_context_factory.cc",
@@ -34,6 +37,7 @@ source_set("lib") {
     "//ui/events",
     "//ui/gfx",
     "//ui/gfx/geometry",
+    "//ui/keyboard:mojom",
     "//ui/message_center",
     "//ui/mojo/init",
     "//ui/platform_window/stub",
@@ -52,4 +56,8 @@ mojo_native_application("mus") {
   deps = [
     ":lib",
   ]
+
+  data_deps = [
+    "//components/mus",
+  ]
 }