Change transport dib API to not make copies of SharedMemoryHandle.

ui/surface/transport_dib.h

Index: ui/surface/transport_dib.h
diff --git a/ui/surface/transport_dib.h b/ui/surface/transport_dib.h
index fa2d13283e12d1883a59eef434888bb01886c61a..49afb3e046c4ed4d4a63b832a187caad5017bfc9 100644
--- a/ui/surface/transport_dib.h
+++ b/ui/surface/transport_dib.h
@@ -135,9 +135,8 @@ class SURFACE_EXPORT TransportDIB {
   // on the wire.
   Id id() const;
 
-  // Return a handle to the underlying shared memory. This can be sent over the
-  // wire to give this transport DIB to another process.
-  Handle handle() const;
+  // Returns a pointer to the SharedMemory object that backs the transport dib.
+  base::SharedMemory* shared_memory();
 
  private:
   TransportDIB();