Aura overlay scrollbars shouldn't invalidate thumb on scroll or enabled state.

third_party/WebKit/Source/platform/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/libfuzzer/fuzzer_test.gni")
 import("//testing/test.gni")
 import("//third_party/WebKit/public/public_features.gni")
 import("//third_party/WebKit/Source/build/scripts/scripts.gni")
@@ skipping 1775 matching lines @@
     "scheduler/renderer/deadline_task_runner_unittest.cc",
     "scheduler/renderer/idle_time_estimator_unittest.cc",
     "scheduler/renderer/renderer_scheduler_impl_unittest.cc",
     "scheduler/renderer/task_cost_estimator_unittest.cc",
     "scheduler/renderer/task_queue_throttler_unittest.cc",
     "scheduler/renderer/user_model_unittest.cc",
     "scheduler/renderer/web_frame_scheduler_impl_unittest.cc",
     "scheduler/renderer/web_view_scheduler_impl_unittest.cc",
     "scheduler/renderer/webthread_impl_for_renderer_scheduler_unittest.cc",
     "scroll/ScrollableAreaTest.cpp",
+    "scroll/ScrollbarThemeOverlayTest.cpp",
     "testing/ArenaTestHelpers.h",
     "testing/TreeTestHelpers.cpp",
     "testing/TreeTestHelpers.h",
     "text/BidiResolverTest.cpp",
     "text/CharacterTest.cpp",
     "text/DateTimeFormatTest.cpp",
     "text/HyphenationTest.cpp",
     "text/SegmentedStringTest.cpp",
     "text/TextBreakIteratorTest.cpp",
     "text/TextEncodingDetectorTest.cpp",
@@ skipping 264 matching lines @@
     "//third_party/WebKit/Source:config",
     "//third_party/WebKit/Source:inside_blink",
   ]
 
   deps = [
     ":test_support",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }