Remove DisplayChangeObserver ash dependencies.

ui/display/manager/display_string_provider.h

+// 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.
+
+#ifndef UI_DISPLAY_MANAGER_DISPLAY_STRING_PROVIDER_H_
+#define UI_DISPLAY_MANAGER_DISPLAY_STRING_PROVIDER_H_
+
+#include <string>
+
+namespace display {
+
+// Provides generic display names loaded from resources.
+class DisplayStringProvider {
+ public:
+  virtual ~DisplayStringProvider() {}
+
+  virtual std::string GetInternalDisplayNameString() = 0;
+  virtual std::string GetVirtualDisplayNameString() = 0;
+  virtual std::string GetUnknownDisplayNameString() = 0;

[oshima, 2016/11/30 18:17:09]

Using a interface looks overkill. Can't you just inject string and update when
locale changed? Or you can just define in ui/. 

[kylechar, 2016/11/30 21:46:03]

I discussed this with sadrul briefly. We will need the strings in ui/ eventually
so I'll go with that solution. I will need to split the //ui/display target into
two though because //ui/base depends on //ui/display now, so we can't use
localization utilities in //ui/display.

Finishing up that split now as a separate CL since it will be rather large.

+};
+
+}  // namespace display
+
+#endif  // UI_DISPLAY_MANAGER_DISPLAY_STRING_PROVIDER_H_