[Payment Request] Picker view + showcase integration + egtests

ios/showcase/payments/BUILD.gn

 # Copyright 2017 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("payments") {
   sources = [
     "sc_payments_editor_coordinator.h",
     "sc_payments_editor_coordinator.mm",
+    "sc_payments_picker_coordinator.h",
+    "sc_payments_picker_coordinator.mm",
   ]
   deps = [
     "//base",
     "//ios/chrome/browser/payments:payments_ui",
     "//ios/chrome/browser/payments/cells",
     "//ios/chrome/browser/ui/collection_view/cells",
     "//ios/chrome/browser/ui/settings/cells",
     "//ios/showcase/common",
   ]
   libs = [ "UIKit.framework" ]
   configs += [ "//build/config/compiler:enable_arc" ]
 }
 
 source_set("eg_tests") {
   testonly = true
   sources = [
     "sc_payments_editor_egtest.mm",
+    "sc_payments_picker_egtest.mm",
   ]
   deps = [
     "//base",
     "//components/strings",
     "//ios/chrome/browser/payments:payments_ui",
     "//ios/chrome/browser/ui/settings",
     "//ios/showcase/test",
     "//ios/third_party/earl_grey",
     "//ui/base",
   ]
   configs += [ "//build/config/compiler:enable_arc" ]
 }