Remove DisplayChangeObserver ash dependencies.

ash/display/window_tree_host_manager.cc

Index: ash/display/window_tree_host_manager.cc
diff --git a/ash/display/window_tree_host_manager.cc b/ash/display/window_tree_host_manager.cc
index f4b583aa8082cffc0fa6eb296b808370a331d4b5..dde5259d7a72f5ff98abe78a76d480200665259b 100644
--- a/ash/display/window_tree_host_manager.cc
+++ b/ash/display/window_tree_host_manager.cc
@@ -29,7 +29,6 @@
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_task_runner_handle.h"
-#include "grit/ash_strings.h"
 #include "ui/aura/client/capture_client.h"
 #include "ui/aura/client/focus_client.h"
 #include "ui/aura/client/screen_position_client.h"
@@ -837,14 +836,6 @@ ui::DisplayConfigurator* WindowTreeHostManager::display_configurator() {
 }
 #endif
 
-std::string WindowTreeHostManager::GetInternalDisplayNameString() {
-  return l10n_util::GetStringUTF8(IDS_ASH_INTERNAL_DISPLAY_NAME);
-}
-
-std::string WindowTreeHostManager::GetUnknownDisplayNameString() {
-  return l10n_util::GetStringUTF8(IDS_ASH_STATUS_TRAY_UNKNOWN_DISPLAY_NAME);
-}
-
 ui::EventDispatchDetails WindowTreeHostManager::DispatchKeyEventPostIME(
     ui::KeyEvent* event) {
   // Getting the active root window to dispatch the event. This isn't