Add NativePixmapHandle type & interface for exporting them

ui/gfx/gpu_memory_buffer.h

Index: ui/gfx/gpu_memory_buffer.h
diff --git a/ui/gfx/gpu_memory_buffer.h b/ui/gfx/gpu_memory_buffer.h
index 263a0ef41da40ddd140556c2ccc0d73d51a30afe..56ce36613fe0dc979c6464e4fac4773c066859c2 100644
--- a/ui/gfx/gpu_memory_buffer.h
+++ b/ui/gfx/gpu_memory_buffer.h
@@ -11,6 +11,10 @@
 #include "ui/gfx/buffer_types.h"
 #include "ui/gfx/gfx_export.h"
 
+#if defined(USE_OZONE)
+#include "ui/gfx/native_pixmap_handle_ozone.h"
+#endif
+
 extern "C" typedef struct _ClientBuffer* ClientBuffer;
 
 namespace gfx {
@@ -32,6 +36,9 @@ struct GFX_EXPORT GpuMemoryBufferHandle {
   GpuMemoryBufferType type;
   GpuMemoryBufferId id;
   base::SharedMemoryHandle handle;
+#if defined(USE_OZONE)
+  NativePixmapHandle native_pixmap_handle;

[dshwang, 2015/08/05 13:30:10]

we can pass |dmabuf_fd| via GpuMemoryBufferHandle::handle, but use
NativePixmapHandle::fd instead. GpuMemoryBufferHandle::handle is not used in
ozone.
So additional member is |stride|. I'm not sure if we will add additional
metadata. imho, it looks over-generalized.

[reveman, 2015/08/05 13:58:52]

I prefer having the fd as part of |native_pixmap_handle|.

[dshwang, 2015/08/05 14:12:51]

I see. lgtm

+#endif
 };
 
 base::trace_event::MemoryAllocatorDumpGuid GFX_EXPORT