Fix gradient background invalidation when HTML size changes

third_party/WebKit/Source/core/paint/BUILD.gn

 # Copyright 2016 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("//third_party/WebKit/Source/core/core.gni")
 
 blink_core_sources("paint") {
   split_count = 2
   sources = [
     "BackgroundImageGeometry.cpp",
@@ skipping 172 matching lines @@
     "ThemePainterDefault.cpp",
     "ThemePainterDefault.h",
     "ThemePainterMac.h",
     "ThemePainterMac.mm",
     "Transform3DRecorder.cpp",
     "Transform3DRecorder.h",
     "TransformRecorder.cpp",
     "TransformRecorder.h",
     "VideoPainter.cpp",
     "VideoPainter.h",
+    "ViewPaintInvalidator.cpp",
+    "ViewPaintInvalidator.h",
     "ViewPainter.cpp",
     "ViewPainter.h",
   ]
 
   configs += [
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     "//build/config/compiler:no_size_t_to_int_warning",
   ]
 }