mash: make Env::last_mouse_location() accurate for Mus

ui/aura/test/aura_test_helper.cc

Index: ui/aura/test/aura_test_helper.cc
diff --git a/ui/aura/test/aura_test_helper.cc b/ui/aura/test/aura_test_helper.cc
index 7c9e5cbb5705cfc8eac579464dc8519c9bd015a9..b215374acb0c984b96512371969c76d722d0b482 100644
--- a/ui/aura/test/aura_test_helper.cc
+++ b/ui/aura/test/aura_test_helper.cc
@@ -109,6 +109,9 @@ void AuraTestHelper::SetUp(ui::ContextFactory* context_factory,
   // above.
   env_helper.SetMode(env_mode);
   env_helper.SetWindowTreeClient(window_tree_client_);
+  // Tests assume they can set the mouse location on Env() and have it reflected
+  // in tests.
+  env_helper.SetAlwaysUseLastMouseLocation(true);
   Env::GetInstance()->SetActiveFocusClient(focus_client_.get(), nullptr);
   Env::GetInstance()->set_context_factory(context_factory);
   Env::GetInstance()->set_context_factory_private(context_factory_private);