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

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

Index: ui/ozone/platform/drm/gpu/gbm_buffer.cc
diff --git a/ui/ozone/platform/drm/gpu/gbm_buffer.cc b/ui/ozone/platform/drm/gpu/gbm_buffer.cc
index c92ba44240b58351d82a76fbabd96cab1e87b388..9f4d63d1978d6233068819f27a45c654b4d073f9 100644
--- a/ui/ozone/platform/drm/gpu/gbm_buffer.cc
+++ b/ui/ozone/platform/drm/gpu/gbm_buffer.cc
@@ -53,6 +53,7 @@ scoped_refptr<GbmBuffer> GbmBuffer::CreateBuffer(
   TRACE_EVENT2("drm", "GbmBuffer::CreateBuffer", "device",
                gbm->device_path().value(), "size", size.ToString());
   unsigned flags = GBM_BO_USE_RENDERING;
+  // GBM_BO_USE_SCANOUT is the hint of x-tiling.
   if (scanout)
     flags |= GBM_BO_USE_SCANOUT;
   gbm_bo* bo = gbm_bo_create(gbm->device(), size.width(), size.height(),
@@ -147,4 +148,17 @@ bool GbmPixmap::ShouldApplyScaling(const gfx::Rect& display_bounds,
   return pixmap_size != *required_size;
 }
 
+NativePixmap::BufferUsage GbmPixmap::GetBufferUsage() const {
+  return buffer_->GetFramebufferId() ? SCANOUT : MAP;
+}
+
+void* GbmPixmap::Map() {
+  NOTREACHED();
+  return nullptr;
+}
+
+void GbmPixmap::Unmap() {
+  NOTREACHED();
+}
+
 }  // namespace ui