Adds special support to the device manager for keyboards devices.

ash/display/display_change_observer_chromeos.cc

Index: ash/display/display_change_observer_chromeos.cc
diff --git a/ash/display/display_change_observer_chromeos.cc b/ash/display/display_change_observer_chromeos.cc
index 047d903e8b434cf355a7be6f4bde63b8422f7337..40e0c826ad4a88ae8e76723a66552498c64e4f4a 100644
--- a/ash/display/display_change_observer_chromeos.cc
+++ b/ash/display/display_change_observer_chromeos.cc
@@ -7,6 +7,8 @@
 #include <algorithm>
 #include <map>
 #include <set>
+#include <string>
+#include <utility>
 #include <vector>
 
 #include "ash/ash_switches.h"
@@ -287,9 +289,11 @@ float DisplayChangeObserver::FindDeviceScaleFactor(float dpi) {
   return 1.0f;
 }
 
-void DisplayChangeObserver::OnInputDeviceConfigurationChanged() {
+void DisplayChangeObserver::OnTouchscreenDeviceConfigurationChanged() {
   OnDisplayModeChanged(
       Shell::GetInstance()->display_configurator()->cached_displays());
 }
 
+void DisplayChangeObserver::OnKeyboardDeviceConfigurationChanged() {}
+
 }  // namespace ash