Move DevTools out of ash and turn it to a component.

ash/BUILD.gn

Index: ash/BUILD.gn
diff --git a/ash/BUILD.gn b/ash/BUILD.gn
index 26914aa76c270f6d04ea375cf2c6a096bd806577..ed95095a89b0160a95c29af040cdcc892f1ed827 100644
--- a/ash/BUILD.gn
+++ b/ash/BUILD.gn
@@ -79,19 +79,6 @@ component("ash") {
     "default_accessibility_delegate.h",
     "default_wallpaper_delegate.cc",
     "default_wallpaper_delegate.h",
-    "devtools/ash_devtools_css_agent.cc",
-    "devtools/ash_devtools_css_agent.h",
-    "devtools/ash_devtools_dom_agent.cc",
-    "devtools/ash_devtools_dom_agent.h",
-    "devtools/ui_element.cc",
-    "devtools/ui_element.h",
-    "devtools/ui_element_delegate.h",
-    "devtools/view_element.cc",
-    "devtools/view_element.h",
-    "devtools/widget_element.cc",
-    "devtools/widget_element.h",
-    "devtools/window_element.cc",
-    "devtools/window_element.h",
     "display/ash_display_controller.cc",
     "display/ash_display_controller.h",
     "display/cursor_window_controller.cc",
@@ -851,6 +838,7 @@ component("ash") {
     "//components/session_manager:base",
     "//components/signin/core/account_id",
     "//components/ui_devtools",
+    "//components/ui_devtools/views",
     "//components/user_manager",
     "//components/vector_icons",
     "//components/wallpaper",
@@ -1159,7 +1147,6 @@ source_set("common_unittests") {
     "accelerators/spoken_feedback_toggler_unittest.cc",
     "ash_touch_exploration_manager_chromeos_unittest.cc",
     "autoclick/autoclick_unittest.cc",
-    "devtools/ash_devtools_unittest.cc",
     "display/display_configuration_controller_unittest.cc",
     "drag_drop/drag_image_view_unittest.cc",
     "first_run/first_run_helper_unittest.cc",