mojo/gpu: use SharedBuffer instead of base::SharedMemory with hacks

mojo/services/gles2/mojo_buffer_backing.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 "mojo/services/gles2/mojo_buffer_backing.h"
+
+namespace mojo {
+namespace gles2 {
+
+MojoBufferBacking::MojoBufferBacking(mojo::ScopedSharedBufferHandle handle,
+                                     void* memory,
+                                     size_t size)
+    : handle_(handle.Pass()), memory_(memory), size_(size) {}
+
+MojoBufferBacking::~MojoBufferBacking() { mojo::UnmapBuffer(memory_); }
+
+// static
+scoped_ptr<gpu::BufferBacking> MojoBufferBacking::Create(
+    mojo::ScopedSharedBufferHandle handle,
+    size_t size) {
+  void* memory = NULL;
+  MojoResult result = mojo::MapBuffer(
+      handle.get(), 0, size, &memory, MOJO_MAP_BUFFER_FLAG_NONE);
+  if (result != MOJO_RESULT_OK)
+    return scoped_ptr<BufferBacking>();
+  DCHECK(memory);
+  return scoped_ptr<BufferBacking>(
+      new MojoBufferBacking(handle.Pass(), memory, size));
+}
+void* MojoBufferBacking::GetMemory() const { return memory_; }
+size_t MojoBufferBacking::GetSize() const { return size_; }
+
+}  // namespace gles2
+}  // namespace mojo