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

ui/ozone/public/native_pixmap.h

 // 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.
 
 #ifndef UI_OZONE_PUBLIC_NATIVE_PIXMAP_H_
 #define UI_OZONE_PUBLIC_NATIVE_PIXMAP_H_
 
 #include "base/memory/ref_counted.h"
 
 namespace ui {
 
 // This represents a buffer that can be directly imported via GL for
 // rendering, or exported via dma-buf fds.
 class NativePixmap : public base::RefCountedThreadSafe<NativePixmap> {
  public:
   NativePixmap() {}
 
   virtual void* /* EGLClientBuffer */ GetEGLClientBuffer() = 0;
   virtual int GetDmaBufFd() = 0;
   virtual int GetDmaBufPitch() = 0;
 
+  enum BufferUsage {
+    MAP,
+    PERSISTENT_MAP,
+    SCANOUT,
+  };
+  virtual BufferUsage GetBufferUsage() const = 0;
+
+  virtual void* Map() = 0;
+  virtual void Unmap() = 0;
+
  protected:
   virtual ~NativePixmap() {}
 
  private:
   friend class base::RefCountedThreadSafe<NativePixmap>;
 
   DISALLOW_COPY_AND_ASSIGN(NativePixmap);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PUBLIC_NATIVE_PIXMAP_H_