[Web Payments] Add "pencil" edit button to lists.

ui/vector_icons/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.
 
 import("//build/util/branding.gni")
 import("//ui/vector_icons/vector_icons.gni")
 
 aggregate_vector_icons("ui_vector_icons") {
   icon_directory = "."
 
   icons = [
     "back_arrow.1x.icon",
     "back_arrow.icon",
     "business.icon",
     "check_circle.icon",
     "close.1x.icon",
     "close.icon",
+    "edit_pen.icon",

[Mathieu, 2017/05/08 14:08:02]

it's technically a pencil? :) 

Using a pen would mean you can't erase your changes haha

[anthonyvd, 2017/05/08 14:45:54]

Good point, done.

     "error_circle.icon",
     "forward_arrow.1x.icon",
     "forward_arrow.icon",
     "info_outline.icon",
     "location_on.icon",
     "media_router_active.icon",
     "media_router_error.icon",
     "media_router_idle.icon",
     "media_router_warning.icon",
     "microphone.icon",
@@ skipping 10 matching lines @@
 static_library("vector_icons") {
   sources = get_target_outputs(":ui_vector_icons")
   sources += [ "//ui/gfx/vector_icon_types.h" ]
 
   deps = [
     ":ui_vector_icons",
     "//base",
     "//skia",
   ]
 }