Split ios/chrome/app/startup targets to reduce dependencies.

ios/showcase/core/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("core") {
   sources = [
     "app_delegate.h",
     "app_delegate.mm",
     "showcase_model.h",
     "showcase_model.mm",
     "showcase_view_controller.h",
     "showcase_view_controller.mm",
   ]
   deps = [
     "//base",
-    "//ios/chrome/app/startup",
+    "//ios/chrome/app/startup:startup_basic",
     "//ios/showcase/common",
     "//ios/third_party/material_components_ios",
     "//ios/third_party/material_roboto_font_loader_ios",
     "//ui/base",
   ]
   libs = [ "UIKit.framework" ]
   configs += [ "//build/config/compiler:enable_arc" ]
 }
 
 source_set("main") {
@@ skipping 19 matching lines @@
   testonly = true
   sources = [
     "showcase_egtest.mm",
   ]
   deps = [
     "//ios/showcase/test",
     "//ios/third_party/earl_grey",
   ]
   configs += [ "//build/config/compiler:enable_arc" ]
 }