Add a chrome://webapks page.

chrome/browser/resources/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("//chrome/common/features.gni")
 import("//tools/grit/grit_rule.gni")
 
 grit("net_internals_resources") {
   source = "net_internals_resources.grd"
   use_qualified_include = true
@@ skipping 132 matching lines @@
   grit("sync_file_system_internals_resources") {
     source = "sync_file_system_internals_resources.grd"
     use_qualified_include = true
     defines = chrome_grit_defines
     outputs = [
       "grit/sync_file_system_internals_resources.h",
       "sync_file_system_internals_resources.pak",
     ]
     output_dir = "$root_gen_dir/chrome"
   }
+
+  grit("webapks_ui_resources") {
+    source = "webapks_ui_resources.grd"
+    use_qualified_include = true
+    defines = chrome_grit_defines
+    outputs = [
+      "grit/webapks_ui_resources.h",
+      "webapks_ui_resources.pak",
+    ]
+    output_dir = "$root_gen_dir/chrome"
+  }
 }