Show corresponding window/widget/view in UIElement tree when clicking on a UI element.

components/ui_devtools/views/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("//build/config/ui.gni")
 
 source_set("views") {
   cflags = []
   if (is_win) {
     cflags += [ "/wd4800" ]  # Value forced to bool.
   }
 
   sources = [
     "ui_devtools_css_agent.cc",
     "ui_devtools_css_agent.h",
     "ui_devtools_dom_agent.cc",
     "ui_devtools_dom_agent.h",
+    "ui_devtools_overlay_agent.cc",
+    "ui_devtools_overlay_agent.h",
     "ui_element.cc",
     "ui_element.h",
     "ui_element_delegate.h",
     "view_element.cc",
     "view_element.h",
     "widget_element.cc",
     "widget_element.h",
     "window_element.cc",
     "window_element.h",
   ]
@@ skipping 25 matching lines @@
     "//skia",
     "//testing/gtest",
     "//ui/aura",
     "//ui/views",
     "//ui/views:test_support",
     "//ui/wm:wm",
   ]
 
   configs += [ "//build/config:precompiled_headers" ]
 }