Aura-Mus: Allocate a LocalSurfaceId on size change

ui/aura/test/mus/test_window_tree.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_AURA_TEST_MUS_TEST_WINDOW_TREE_H_
 #define UI_AURA_TEST_MUS_TEST_WINDOW_TREE_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 76 matching lines @@
 
   // Data from the most recently added/removed transient window.
   const TransientData& transient_data() const { return transient_data_; }
 
   const gfx::Insets& last_client_area() const { return last_client_area_; }
 
   const base::Optional<gfx::Rect>& last_hit_test_mask() const {
     return last_hit_test_mask_;
   }
 
+  const base::Optional<cc::LocalSurfaceId>& last_local_surface_id() const {
+    return last_local_surface_id_;
+  }
+
  private:
   struct Change {
     WindowTreeChangeType type;
     uint32_t id;
   };
 
   void OnChangeReceived(
       uint32_t change_id,
       WindowTreeChangeType type = WindowTreeChangeType::OTHER);
 
@@ skipping 114 matching lines @@
 
   base::Optional<std::unordered_map<std::string, std::vector<uint8_t>>>
       last_new_window_properties_;
 
   TransientData transient_data_;
 
   gfx::Insets last_client_area_;
 
   base::Optional<gfx::Rect> last_hit_test_mask_;
 
+  base::Optional<cc::LocalSurfaceId> last_local_surface_id_;
+
   DISALLOW_COPY_AND_ASSIGN(TestWindowTree);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_TEST_MUS_TEST_WINDOW_TREE_H_