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

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_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",
+  ]
+
+  deps = [
+    "//components/ui_devtools",
+    "//skia",
+    "//ui/aura",
+    "//ui/views",
+    "//ui/wm:wm",
+  ]
+}
+
+source_set("unit_tests") {
+  testonly = true
+
+  cflags = []
+  if (is_win) {
+    cflags += [ "/wd4800" ]  # Value forced to bool.
+  }
+
+  sources = [
+    "ui_devtools_unittest.cc",
+  ]
+
+  deps = [
+    ":views",
+    "//components/ui_devtools",
+    "//skia",
+    "//testing/gtest",
+    "//ui/aura",
+    "//ui/views",
+    "//ui/views:test_support",
+    "//ui/wm:wm",
+  ]
+
+  configs += [ "//build/config:precompiled_headers" ]
+}