exo: Recreate Surface resources on context lost.

ash/sysui/stub_context_factory.h

 // Copyright 2016 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 ASH_SYSUI_STUB_CONTEXT_FACTORY_H_
 #define ASH_SYSUI_STUB_CONTEXT_FACTORY_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 26 matching lines @@
   cc::SharedBitmapManager* GetSharedBitmapManager() override;
   gpu::GpuMemoryBufferManager* GetGpuMemoryBufferManager() override;
   cc::TaskGraphRunner* GetTaskGraphRunner() override;
   std::unique_ptr<cc::SurfaceIdAllocator> CreateSurfaceIdAllocator() override;
   cc::SurfaceManager* GetSurfaceManager() override;
   void ResizeDisplay(ui::Compositor* compositor,
                      const gfx::Size& size) override;
   void SetAuthoritativeVSyncInterval(ui::Compositor* compositor,
                                      base::TimeDelta interval) override {}
   void SetOutputIsSecure(ui::Compositor* compositor, bool secure) override {}
+  void AddObserver(ui::ContextFactoryObserver* observer) override {}
+  void RemoveObserver(ui::ContextFactoryObserver* observer) override {}
 
   uint32_t next_surface_id_namespace_;
   std::unique_ptr<cc::SingleThreadTaskGraphRunner> task_graph_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(StubContextFactory);
 };
 
 }  // namespace sysui
 }  // namespace ash
 
 #endif  // ASH_SYSUI_STUB_CONTEXT_FACTORY_H_