Move chromeos::EventRewriter to //ui/chromeos/events

ui/chromeos/events/BUILD.gn

+# Copyright 2017 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")
+import("//ui/ozone/ozone.gni")
+
+assert(is_chromeos)
+
+source_set("events") {
+  output_name = "ui_chromeos_events"
+  sources = [
+    "event_rewriter_chromeos.cc",
+    "event_rewriter_chromeos.h",
+    "pref_names.cc",
+    "pref_names.h",
+  ]
+  deps = [
+    "//base",
+    "//chromeos",
+    "//ui/base/ime",
+    "//ui/events",
+    "//ui/events:dom_keycode_converter",
+    "//ui/events/devices",
+  ]
+  if (use_x11 || ozone_platform_x11) {
+    deps += [
+      "//ui/base/x",
+      "//ui/events/keycodes:x11",
+    ]
+  }
+}