exo: Fix multi-display hardware cursor

ui/aura/test/test_cursor_client.cc

Index: ui/aura/test/test_cursor_client.cc
diff --git a/ui/aura/test/test_cursor_client.cc b/ui/aura/test/test_cursor_client.cc
index f54f92d89ab9d6d18e9d7893a137ab709427348d..72f3a05697559b4de0116464c610e177cff503dc 100644
--- a/ui/aura/test/test_cursor_client.cc
+++ b/ui/aura/test/test_cursor_client.cc
@@ -5,6 +5,7 @@
 #include "ui/aura/test/test_cursor_client.h"
 
 #include "ui/aura/client/cursor_client_observer.h"
+#include "ui/display/display.h"
 
 namespace aura {
 namespace test {
@@ -68,6 +69,11 @@ bool TestCursorClient::IsMouseEventsEnabled() const {
 
 void TestCursorClient::SetDisplay(const display::Display& display) {}
 
+const display::Display& TestCursorClient::GetDisplay() const {
+  static const display::Display display;
+  return display;
+}
+
 void TestCursorClient::LockCursor() {
   cursor_lock_count_++;
 }