Adds DisplayErrorDialog to show the error message of the failure of mirroring to the users.

ash/display/output_configurator_animation.cc

Index: ash/display/output_configurator_animation.cc
diff --git a/ash/display/output_configurator_animation.cc b/ash/display/output_configurator_animation.cc
index 9c19a5019cc8d6032662da628180bd05676e5298..5cd0779fd2ef15684243b22accd32ec866fc4ff7 100644
--- a/ash/display/output_configurator_animation.cc
+++ b/ash/display/output_configurator_animation.cc
@@ -4,6 +4,7 @@
 
 #include "ash/display/output_configurator_animation.h"
 
+#include "ash/display/display_error_dialog.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "base/bind.h"
@@ -209,6 +210,7 @@ void OutputConfiguratorAnimation::OnDisplayModeChanged() {
 void OutputConfiguratorAnimation::OnDisplayModeChangeFailed() {
   if (!hiding_layers_.empty())
     StartFadeInAnimation();
+  DisplayErrorDialog::ShowDialog();
 }
 
 void OutputConfiguratorAnimation::ClearHidingLayers() {