Remove DisplayChangeObserver ash dependencies.

ash/display/ash_display_string_provider.cc

Index: ash/display/ash_display_string_provider.cc
diff --git a/ash/display/ash_display_string_provider.cc b/ash/display/ash_display_string_provider.cc
new file mode 100644
index 0000000000000000000000000000000000000000..782cb49213c430bdf9c85e51a8d2d846bfb0473d
--- /dev/null
+++ b/ash/display/ash_display_string_provider.cc
@@ -0,0 +1,24 @@
+// 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.
+
+#include "ash/display/ash_display_string_provider.h"
+
+#include "ash/common/strings/grit/ash_strings.h"
+#include "ui/base/l10n/l10n_util.h"
+
+namespace ash {
+
+std::string AshDisplayStringProvider::GetInternalDisplayNameString() {
+  return l10n_util::GetStringUTF8(IDS_ASH_INTERNAL_DISPLAY_NAME);
+}
+
+std::string AshDisplayStringProvider::GetVirtualDisplayNameString() {
+  return l10n_util::GetStringUTF8(IDS_ASH_VIRTUAL_DISPLAY_NAME);
+}
+
+std::string AshDisplayStringProvider::GetUnknownDisplayNameString() {
+  return l10n_util::GetStringUTF8(IDS_ASH_STATUS_TRAY_UNKNOWN_DISPLAY_NAME);
+}
+
+}  // namespace ash