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

ui/aura/test/aura_test_base.h

Index: ui/aura/test/aura_test_base.h
diff --git a/ui/aura/test/aura_test_base.h b/ui/aura/test/aura_test_base.h
index 1f690c6d33d3cc2889961a755a5b7989aae48639..f79283d7889a15522e8467432b00000763c9e8eb 100644
--- a/ui/aura/test/aura_test_base.h
+++ b/ui/aura/test/aura_test_base.h
@@ -161,6 +161,18 @@ class AuraTestBaseWithType : public AuraTestBase,
   DISALLOW_COPY_AND_ASSIGN(AuraTestBaseWithType);
 };
 
+class AuraTestBaseMus : public AuraTestBase {
+ public:
+  AuraTestBaseMus();
+  ~AuraTestBaseMus() override;
+
+  // AuraTestBase:
+  void SetUp() override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(AuraTestBaseMus);
+};
+
 }  // namespace test
 }  // namespace aura