components: Add Exosphere component.

components/exo/shared_memory.h

+// Copyright 2015 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 COMPONENTS_EXO_SHARED_MEMORY_H_
+#define COMPONENTS_EXO_SHARED_MEMORY_H_
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/shared_memory.h"
+#include "ui/gfx/buffer_types.h"
+#include "ui/gfx/geometry/size.h"
+
+namespace exo {
+class Buffer;
+
+// Shared memory abstraction. Provides a wrapper around base::SharedMemory
+// with functionality to create buffers from the memory to use for display.
+class SharedMemory {
+ public:
+  explicit SharedMemory(const base::SharedMemoryHandle& handle);
+  ~SharedMemory();
+
+  // Creates a buffer from the shared memory. The buffer is created offset bytes
+  // into the memory and has width and height as specified. The stride
+  // arguments specifies the number of bytes from beginning of one row to the
+  // beginning of the next. The format is the pixel format of the buffer and
+  // must be one of RGBX_8888, RGBA_8888, BGRX_8888, BGRA_8888.
+  scoped_ptr<Buffer> CreateBuffer(const gfx::Size& size,
+                                  gfx::BufferFormat format,
+                                  unsigned offset,
+                                  int stride);
+
+ private:
+  base::SharedMemory shared_memory_;
+
+  DISALLOW_COPY_AND_ASSIGN(SharedMemory);
+};
+
+}  // namespace exo
+
+#endif  // COMPONENTS_EXO_SHARED_MEMORY_H_