[geary/wip/save-sent-713263] Add UnownedBytesBuffer iface to OffsetBuffer

[Charles Lindsay <clindsay src gnome org>]

commit 5c942d4b8ff4ca8cecbba06526a56e0199e68fb6
Author: Charles Lindsay <chaz yorba org>
Date:   Tue Jan 28 16:58:32 2014 -0800

    Add UnownedBytesBuffer iface to OffsetBuffer

 src/engine/memory/memory-offset-buffer.vala |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)
---
diff --git a/src/engine/memory/memory-offset-buffer.vala b/src/engine/memory/memory-offset-buffer.vala
index a7193ee..cd7ea78 100644
--- a/src/engine/memory/memory-offset-buffer.vala
+++ b/src/engine/memory/memory-offset-buffer.vala
@@ -8,7 +8,7 @@
  * A buffer that's simply an offset into an existing buffer.
  */
 
-public class Geary.Memory.OffsetBuffer : Geary.Memory.Buffer {
+public class Geary.Memory.OffsetBuffer : Geary.Memory.Buffer, Geary.Memory.UnownedBytesBuffer {
     /**
      * { inheritDoc}
      */
@@ -37,4 +37,11 @@ public class Geary.Memory.OffsetBuffer : Geary.Memory.Buffer {
             bytes = new Bytes.from_bytes(buffer.get_bytes(), offset, buffer.size - offset);
         return bytes;
     }
+    
+    /**
+     * { inheritDoc}
+     */
+    public unowned uint8[] to_unowned_uint8_array() {
+        return get_bytes().get_data();
+    }
 }