Implement DRM Native Pixmap using prime buffer

ui/ozone/platform/drm/common/client_native_pixmap_dmabuf.cc

+// Copyright 2016 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/common/client_native_pixmap_dmabuf.h"
+
+#include <fcntl.h>
+#include <stddef.h>
+#include <sys/mman.h>
+#include <xf86drm.h>
+
+#include "base/process/memory.h"
+#include "base/trace_event/trace_event.h"
+
+namespace ui {
+
+// static
+scoped_ptr<ClientNativePixmap> ClientNativePixmapDmaBuf::ImportFromDmabuf(
+    int dmabuf_fd,
+    const gfx::Size& size,
+    int stride) {
+  DCHECK_GE(dmabuf_fd, 0);
+  return make_scoped_ptr(new ClientNativePixmapDmaBuf(dmabuf_fd, size, stride));
+}
+
+ClientNativePixmapDmaBuf::ClientNativePixmapDmaBuf(int dmabuf_fd,
+                                                   const gfx::Size& size,
+                                                   int stride)
+    : size_(size), stride_(stride), data_(nullptr) {

[spang, 2016/03/21 23:24:20]

You don't need to initialize data_ here and in the body.

[vignatti (out of this project), 2016/03/22 20:24:29]

Done.

+  TRACE_EVENT0("nativepixmap", "ClientNativePixmapDmaBuf");

[spang, 2016/03/21 23:24:20]

Please use the "drm" category.

[vignatti (out of this project), 2016/03/22 20:24:29]

Done.

+  size_t map_size = stride_ * size_.height();
+  data_ = mmap(nullptr, map_size, (PROT_READ | PROT_WRITE), MAP_SHARED,
+               dmabuf_fd, 0);
+  DCHECK_NE(data_, MAP_FAILED);
+}
+
+ClientNativePixmapDmaBuf::~ClientNativePixmapDmaBuf() {
+  TRACE_EVENT0("nativepixmap", "~ClientNativePixmapDmaBuf");

[spang, 2016/03/21 23:24:20]

Also here

[vignatti (out of this project), 2016/03/22 20:24:29]

Done.

+  size_t size = stride_ * size_.height();
+  int ret = munmap(data_, size);
+  DCHECK(!ret) << "fail to munmap a dmabuf.";

[spang, 2016/03/21 23:24:20]

DPCHECK(!ret);

Don't really need a message for DCHECK.

[vignatti (out of this project), 2016/03/22 20:24:29]

Done.

+}
+
+void* ClientNativePixmapDmaBuf::Map() {
+  return data_;
+}
+
+void ClientNativePixmapDmaBuf::Unmap() {}
+
+void ClientNativePixmapDmaBuf::GetStride(int* stride) const {
+  *stride = stride_;
+}
+
+}  // namespace ui