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

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 b18238e893c6d21834add54e6d4a862013579af5..a04bd6a3ea16f002ed5ed245fa89015471fd4ea6 100644
--- a/ui/ozone/platform/drm/gpu/gbm_buffer.cc
+++ b/ui/ozone/platform/drm/gpu/gbm_buffer.cc
@@ -31,8 +31,10 @@ namespace ui {
 
 GbmBuffer::GbmBuffer(const scoped_refptr<GbmDevice>& gbm,
                      gbm_bo* bo,
+                     gfx::BufferFormat format,
                      gfx::BufferUsage usage)
     : GbmBufferBase(gbm, bo, usage == gfx::BufferUsage::SCANOUT),
+      format_(format),
       usage_(usage) {}
 
 GbmBuffer::~GbmBuffer() {
@@ -58,7 +60,7 @@ scoped_refptr<GbmBuffer> GbmBuffer::CreateBuffer(
   if (!bo)
     return nullptr;
 
-  scoped_refptr<GbmBuffer> buffer(new GbmBuffer(gbm, bo, usage));
+  scoped_refptr<GbmBuffer> buffer(new GbmBuffer(gbm, bo, format, usage));
   if (use_scanout && !buffer->GetFramebufferId())
     return nullptr;
 
@@ -142,7 +144,7 @@ int GbmPixmap::GetDmaBufPitch() const {
 }
 
 gfx::BufferFormat GbmPixmap::GetBufferFormat() const {
-  return GetBufferFormatFromFourCCFormat(buffer_->GetFramebufferPixelFormat());
+  return buffer_->GetFormat();
 }
 
 gfx::Size GbmPixmap::GetBufferSize() const {