[iOS Clean] Created OverlayService.

ios/clean/chrome/browser/ui/overlay_service/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("overlay_service") {

[marq (ping after 24h), 2017/06/23 10:42:01]

Nit: I preferred just calling this directory 'overlays', since we already have
'commands', 'animators', etc.

+  public_deps = [
+    ":overlay_service_headers",
+  ]
+
+  deps = [
+    "//ios/clean/chrome/browser/ui/overlay_service/internal",
+  ]
+}
+
+source_set("overlay_service_headers") {
+  sources = [
+    "browser_coordinator+overlay_support.h",
+    "overlay_service.h",
+    "overlay_service_factory.h",
+  ]
+
+  configs += [ "//build/config/compiler:enable_arc" ]
+
+  deps = [
+    "//base",
+    "//components/keyed_service/core",
+    "//components/keyed_service/ios",
+    "//ios/chrome/browser/browser_state",
+    "//ios/chrome/browser/web_state_list",
+    "//ios/clean/chrome/browser/ui/commands",
+    "//ios/shared/chrome/browser/ui/browser_list",
+    "//ios/shared/chrome/browser/ui/commands",
+    "//ios/shared/chrome/browser/ui/coordinators",
+    "//ios/web",
+  ]
+}