ozone: Allocate scanout buffers according to KMS modifiers.

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

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_OZONE_PLATFORM_DRM_GPU_CRTC_CONTROLLER_H_
 #define UI_OZONE_PLATFORM_DRM_GPU_CRTC_CONTROLLER_H_
 
 #include <stddef.h>
 #include <stdint.h>
 #include <xf86drmMode.h>
@@ skipping 40 matching lines @@
   // Schedule a page flip event and present the overlays in |planes|.
   bool SchedulePageFlip(HardwareDisplayPlaneList* plane_list,
                         const OverlayPlaneList& planes,
                         bool test_only,
                         scoped_refptr<PageFlipRequest> page_flip_request);
 
   // Returns true if hardware plane with z_order equal to |z_order| can support
   // |fourcc_format| format.
   bool IsFormatSupported(uint32_t fourcc_format, uint32_t z_order) const;
 
+  // Returns a vector of format modifiers for the given fourcc format
+  // on this CRTCs primary plane. A format modifier describes the
+  // actual layout of the buffer, such as whether it's linear, tiled
+  // one way or another or maybe compressed. Except for generic
+  // modifiers such as DRM_FORMAT_MOD_NONE (linear), the modifier
+  // values are 64 bit values that we don't understand at this
+  // level. We pass the modifers to gbm_bo_create_with_modifiers() and
+  // gbm will pick a modifier as it allocates the bo.
+  std::vector<uint64_t> GetFormatModifiers(uint32_t fourcc_format);
+
   // Called if the page flip event wasn't scheduled (ie: page flip fails). This
   // will then signal the request such that the caller doesn't wait for the
   // event forever.
   void SignalPageFlipRequest(gfx::SwapResult result);
 
   // Called when the page flip event occurred. The event is provided by the
   // kernel when a VBlank event finished. This allows the controller to
   // update internal state and propagate the update to the surface.
   // The tuple (seconds, useconds) represents the event timestamp. |seconds|
   // represents the number of seconds while |useconds| represents the
@@ skipping 30 matching lines @@
 
   // The time of the last page flip event as reported by the kernel callback.
   uint64_t time_of_last_flip_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(CrtcController);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_DRM_GPU_CRTC_CONTROLLER_H_