[iOS Clean] Added dialogs UI support.

ios/clean/chrome/browser/ui/dialogs/BUILD.gn

+# Copyright 2016 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.
+
+source_set("dialogs_internal") {
+  sources = [
+    "dialog_mediator+internal.h",
+    "dialog_mediator.h",
+    "dialog_mediator.mm",
+  ]
+
+  configs += [ "//build/config/compiler:enable_arc" ]
+
+  deps = [
+    ":dialogs_ui",
+    "//base",
+    "//ios/clean/chrome/browser/ui/commands",
+    "//ios/shared/chrome/browser/ui/commands",
+  ]
+}
+
+source_set("dialogs_ui") {
+  sources = [
+    "dialog_button_item.h",
+    "dialog_button_item.mm",
+    "dialog_consumer.h",
+    "dialog_text_field_item.h",
+    "dialog_text_field_item.mm",
+    "dialog_view_controller.h",
+    "dialog_view_controller.mm",
+  ]
+
+  configs += [ "//build/config/compiler:enable_arc" ]
+
+  deps = [
+    "//base",
+    "//components/strings",
+    "//ios/chrome/app/strings",
+    "//ios/clean/chrome/browser/ui/commands",
+    "//ui/base",
+  ]
+}