Fix black screen when switching primary display without bounds change

ui/ozone/platform/drm/gpu/gbm_buffer_base.h

 // Copyright 2014 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_OZONE_PLATFORM_DRM_GPU_GBM_BUFFER_BASE_H_
 #define UI_OZONE_PLATFORM_DRM_GPU_GBM_BUFFER_BASE_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
@@ skipping 12 matching lines @@
 class GbmBufferBase : public ScanoutBuffer {
  public:
   gbm_bo* bo() const { return bo_; }
   const scoped_refptr<GbmDevice>& drm() const { return drm_; }
 
   // ScanoutBuffer:
   uint32_t GetFramebufferId() const override;
   uint32_t GetHandle() const override;
   gfx::Size GetSize() const override;
   uint32_t GetFramebufferPixelFormat() const override;
+  const DrmDevice* GetDrmDevice() const override;
   bool RequiresGlFinish() const override;
 
  protected:
   GbmBufferBase(const scoped_refptr<GbmDevice>& drm,
                 gbm_bo* bo,
                 gfx::BufferFormat format,
                 gfx::BufferUsage usage);
   ~GbmBufferBase() override;
 
  private:
   scoped_refptr<GbmDevice> drm_;
   gbm_bo* bo_;
   uint32_t framebuffer_ = 0;
   uint32_t framebuffer_pixel_format_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(GbmBufferBase);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_DRM_GPU_GBM_BUFFER_BASE_H_