[Payments] Add the pay button, and control its enabled state

chrome/test/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//chrome/common/features.gni")
@@ skipping 563 matching lines @@
       }
       if (is_win || is_linux) {
         # TODO(crbug.com/679127): Investigate why these tests currently break
         # on Mac, and enable them.
         sources += [
           "../browser/ui/views/payments/payment_method_view_controller_interactive_uitest.cc",
           "../browser/ui/views/payments/payment_request_credit_card_editor_interactive_uitest.cc",
           "../browser/ui/views/payments/payment_request_interactive_uitest.cc",
           "../browser/ui/views/payments/payment_request_interactive_uitest_base.cc",
           "../browser/ui/views/payments/payment_request_interactive_uitest_base.h",
+          "../browser/ui/views/payments/payment_sheet_view_controller_interactive_uitest.cc",
         ]
       }
       if (is_linux) {
         if (!is_chromeos) {
           # Desktop linux.
           sources -= [
             # TODO(port): This times out. Attempts have been made to fix the
             # individual failures, but each time I disable a test from these
             # suites, it seems like one or another starts timing out too.
             "../browser/ui/views/keyboard_access_browsertest.cc",
@@ skipping 4583 matching lines @@
 }
 
 if (is_win) {
   loadable_module("conflicts_dll") {
     testonly = true
     sources = [
       "conflicts/conflicts_dll.cc",
     ]
   }
 }