ozone: support gfx::BufferFormat::RGBX_8888 as a native pixmap format.

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

Index: ui/ozone/platform/drm/gpu/gbm_buffer_base.h
diff --git a/ui/ozone/platform/drm/gpu/gbm_buffer_base.h b/ui/ozone/platform/drm/gpu/gbm_buffer_base.h
index e14fa8a9b20c1ac105022c35307d6417bb605cac..63017784244ed7201926fb91cd80d79807537672 100644
--- a/ui/ozone/platform/drm/gpu/gbm_buffer_base.h
+++ b/ui/ozone/platform/drm/gpu/gbm_buffer_base.h
@@ -29,14 +29,17 @@ class GbmBufferBase : public ScanoutBuffer {
   bool RequiresGlFinish() const override;
 
  protected:
-  GbmBufferBase(const scoped_refptr<DrmDevice>& drm, gbm_bo* bo, bool scanout);
+  GbmBufferBase(const scoped_refptr<DrmDevice>& drm,
+                gbm_bo* bo,
+                gfx::BufferFormat format,
+                gfx::BufferUsage usage);
   ~GbmBufferBase() override;
 
  private:
   scoped_refptr<DrmDevice> drm_;
   gbm_bo* bo_;
   uint32_t framebuffer_ = 0;
-  uint32_t fb_pixel_format_ = 0;
+  uint32_t framebuffer_pixel_format_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(GbmBufferBase);
 };