Change mock canvases to paint into SkCanvas

ui/views/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/features.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 import("//ui/base/ui_features.gni")
 import("//ui/ozone/ozone.gni")
 import("//ui/vector_icons/vector_icons.gni")
@@ skipping 895 matching lines @@
   configs += [ "//build/config:precompiled_headers" ]
 
   # Make all deps in this target public so both views_unittests and
   # views_mus_unittests will get them.
   public_deps = [
     ":test_support",
     "//base",
     "//base:i18n",
     "//base/test:test_support",
     "//cc",
+    "//cc/paint",
     "//services/ui/public/interfaces",
     "//skia",
     "//testing/gtest",
     "//third_party/icu",
     "//ui/accessibility",
     "//ui/base",
     "//ui/base:test_support",
     "//ui/base/ime",
     "//ui/compositor:test_support",
     "//ui/events:dom_keycode_converter",
@@ skipping 124 matching lines @@
       "//ui/base:test_support",
       "//ui/compositor",
       "//ui/events:test_support",
       "//ui/gl:test_support",
       "//ui/resources",
       "//ui/resources:ui_test_pak",
       "//ui/strings",
     ]
   }
 }