ozone: Allocate scanout buffer according to KMS modifiers

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

Index: ui/ozone/platform/drm/gpu/hardware_display_controller.h
diff --git a/ui/ozone/platform/drm/gpu/hardware_display_controller.h b/ui/ozone/platform/drm/gpu/hardware_display_controller.h
index 3738cf27d4459d4026e10f755c1b3ccc31d4cf6a..25cb2168f638338dd6d0b722c5e0fad4bfbf4fd2 100644
--- a/ui/ozone/platform/drm/gpu/hardware_display_controller.h
+++ b/ui/ozone/platform/drm/gpu/hardware_display_controller.h
@@ -127,6 +127,12 @@ class HardwareDisplayController {
 
   bool IsFormatSupported(uint32_t fourcc_format, uint32_t z_order) const;
 
+  // Add GBM usage flags to |flags| as needed for the |format| and
+  // |flags| passed in. This lets a controller set additional flags to
+  // make sure the allocated buffer can be scanned out.
+  uint32_t GetFormatModifiers(uint32_t format,
+			      uint64_t *modifiers, uint32_t count);
+
   // Set the hardware cursor to show the contents of |surface|.
   bool SetCursor(const scoped_refptr<ScanoutBuffer>& buffer);