ozone: Implement zero/one-copy texture for Ozone GBM.

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

Index: ui/ozone/platform/drm/gpu/gbm_buffer.h
diff --git a/ui/ozone/platform/drm/gpu/gbm_buffer.h b/ui/ozone/platform/drm/gpu/gbm_buffer.h
index 2cd388f69859a998d81066dfbaffad174c9b8f63..3fe9754f1ce7581a5b6bf39fb4601867e95a64db 100644
--- a/ui/ozone/platform/drm/gpu/gbm_buffer.h
+++ b/ui/ozone/platform/drm/gpu/gbm_buffer.h
@@ -14,6 +14,10 @@
 
 struct gbm_bo;
 
+namespace gfx {
+struct GpuMemoryBufferHandle;
+}
+
 namespace ui {
 
 class GbmDevice;
@@ -38,10 +42,13 @@ class GbmPixmap : public NativePixmap {
   GbmPixmap(const scoped_refptr<GbmBuffer>& buffer);
   bool Initialize();
 
+  bool ExportDmaBuf(int vgem_fd, gfx::GpuMemoryBufferHandle* handle);
+
   // NativePixmap:
   void* GetEGLClientBuffer() override;
   int GetDmaBufFd() override;
   int GetDmaBufPitch() override;
+  BufferUsage GetBufferUsage() const override;
 
   scoped_refptr<GbmBuffer> buffer() { return buffer_; }