ozone: Introduce ClientPixmap and ClientPixmapFactory for non-GPU processes.

ui/ozone/public/client_pixmap.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 UI_OZONE_PUBLIC_CLIENT_PIXMAP_H_
+#define UI_OZONE_PUBLIC_CLIENT_PIXMAP_H_
+
+#include "ui/ozone/ozone_export.h"
+
+namespace ui {
+
+// This represents a buffer that can be written to directly by regular CPU code
+// in non-GPU processes, but can also be read by the GPU.

[reveman, 2015/07/30 16:14:10]

"non-GPU processes", do we need to be this specific here? CPU access to native
pixmaps in the GPU process will mostly like use this class too.

[dshwang, 2015/07/30 16:50:15]

That's true, though we don't have the use case yet. I'll remove "non-GPU
processes"

+// NativePixmap is its counterpart in GPU process.
+class OZONE_EXPORT ClientPixmap {

[reveman, 2015/07/30 16:14:10]

Why the "Native" prefix in one case but not the other? Can you make it
consistent? Pixmap+ClientPixmap or NativePixmap+ClientNativePixmap

[dshwang, 2015/07/30 16:50:15]

Ok, I remain this up to spang. spang, which do you prefer?

[dshwang, 2015/07/31 10:41:04]

Ok, NativePixmap and ClientNativePixmap are chosen.

+ public:
+  virtual ~ClientPixmap() {}
+
+  virtual void* Map() = 0;
+  virtual void Unmap() = 0;
+  virtual int GetStride() const = 0;
+};
+
+}  // namespace ui
+
+#endif  // UI_OZONE_PUBLIC_CLIENT_PIXMAP_H_