ozone: Validate the memory buffer used.

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

 // 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.
 
 #ifndef UI_OZONE_PLATFORM_DRM_COMMON_CLIENT_NATIVE_PIXMAP_DMABUF_H_
 #define UI_OZONE_PLATFORM_DRM_COMMON_CLIENT_NATIVE_PIXMAP_DMABUF_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 11 matching lines @@
   ImportFromDmabuf(int dmabuf_fd, const gfx::Size& size, int stride);
 
   ~ClientNativePixmapDmaBuf() override;
 
   // Overridden from ClientNativePixmap.
   void* Map() override;
   void Unmap() override;
   void GetStride(int* stride) const override;
 
  private:
-  ClientNativePixmapDmaBuf(int dmabuf_fd, const gfx::Size& size, int stride);
+  ClientNativePixmapDmaBuf(int dmabuf_fd,
+                           const gfx::Size& size,
+                           int stride,
+                           size_t map_size);
 
   base::ScopedFD dmabuf_fd_;
+  const size_t map_size_;
   const gfx::Size size_;
   const int stride_;
   void* data_;
 
   DISALLOW_COPY_AND_ASSIGN(ClientNativePixmapDmaBuf);
 };
 
 }  // namespace ui
 
 #endif  // UI_OZONE_PLATFORM_DRM_COMMON_CLIENT_NATIVE_PIXMAP_DMABUF_H_