Add GetDisplayWithDisplayId to display::Screen.

ash/test/ash_test_base.cc

Index: ash/test/ash_test_base.cc
diff --git a/ash/test/ash_test_base.cc b/ash/test/ash_test_base.cc
index 22d4ffda056127df4fa9f020c899d47c7b0c7d16..9696477a3a27bdd6d585e6b92c1a230b876aa361 100644
--- a/ash/test/ash_test_base.cc
+++ b/ash/test/ash_test_base.cc
@@ -216,6 +216,10 @@ void AshTestBase::UpdateDisplay(const std::string& display_specs) {
   DisplayManagerTestApi().UpdateDisplay(display_specs);
 }
 
+int64_t AshTestBase::SetFirstDisplayAsInternalDisplay() {
+  return DisplayManagerTestApi().SetFirstDisplayAsInternalDisplay();
+}
+
 aura::Window* AshTestBase::CurrentContext() {
   return ash_test_helper_->CurrentContext();
 }