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

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

 // 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.
 
 #include "ui/ozone/platform/drm/gpu/gbm_buffer.h"
 
 #include <drm.h>
 #include <fcntl.h>
 #include <gbm.h>
 #include <xf86drm.h>
@@ skipping 33 matching lines @@
 
 // static
 scoped_refptr<GbmBuffer> GbmBuffer::CreateBuffer(
     const scoped_refptr<GbmDevice>& gbm,
     SurfaceFactoryOzone::BufferFormat format,
     const gfx::Size& size,
     bool scanout) {
   TRACE_EVENT2("drm", "GbmBuffer::CreateBuffer", "device",
                gbm->device_path().value(), "size", size.ToString());
   unsigned flags = GBM_BO_USE_RENDERING;
-  if (scanout)
-    flags |= GBM_BO_USE_SCANOUT;
+  // SCANOUT allocates continuous memory, so better for performance even if
+  // |scanout| is false.
+  flags |= GBM_BO_USE_SCANOUT;
   gbm_bo* bo = gbm_bo_create(gbm->device(), size.width(), size.height(),
                              GetGbmFormatFromBufferFormat(format), flags);
   if (!bo)
     return NULL;
 
   scoped_refptr<GbmBuffer> buffer(new GbmBuffer(gbm, bo, scanout));
   if (scanout && !buffer->GetFramebufferId())
     return NULL;
 
   return buffer;
@@ skipping 24 matching lines @@
 }
 
 int GbmPixmap::GetDmaBufFd() {
   return dma_buf_;
 }
 
 int GbmPixmap::GetDmaBufPitch() {
   return gbm_bo_get_stride(buffer_->bo());
 }
 
+NativePixmap::BufferUsage GbmPixmap::GetBufferUsage() const {
+  return buffer_->GetFramebufferId() ? SCANOUT : MAP;
+}
+
+void* GbmPixmap::Map() {
+  NOTREACHED();
+  return nullptr;
+}
+
+void GbmPixmap::Unmap() {
+  NOTREACHED();
+}
+
 }  // namespace ui