Adds ScopedHandleBase::From

mojo/public/cpp/bindings/interface.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 MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_H_
 #define MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_H_
 
 #include <assert.h>
 
 #include "mojo/public/cpp/bindings/message.h"
@@ skipping 45 matching lines @@
   typedef InterfaceHandle<S> Handle;
   typedef ScopedHandleBase<InterfaceHandle<S> > ScopedHandle;
 };
 
 template <>
 struct Interface<mojo::NoInterface> {
   typedef MessagePipeHandle Handle;
   typedef ScopedMessagePipeHandle ScopedHandle;
 };
 
+// Use to convert from a ScopedMessagePipeHandle to an scoped interface
+// handle. For example,
+// ConvertToInterface<OmniboxPage>(message_pip_handle.Pass()),

[vtl, 2014/04/03 14:58:30]

drive-by nit: message_pip -> message_pipe

+// where OmniboxPage names an interface in a mojom file.
+template <typename S>
+typename Interface<S>::ScopedHandle ConvertToInterface(
+    ScopedMessagePipeHandle message_pipe_handle) {
+  return Interface<S>::ScopedHandle(
+      Interface<S>::Handle(message_pipe_handle.release().value()));
+}
 
 // InterfacePipe<S,P> is used to construct a MessagePipe with typed interfaces
 // on either end.
 
 template <typename S, typename P = typename S::_Peer>
 class InterfacePipe {
  public:
   InterfacePipe() {
     typename Interface<S>::Handle h0;
     typename Interface<P>::Handle h1;
     MojoResult result MOJO_ALLOW_UNUSED =
         MojoCreateMessagePipe(h0.mutable_value(), h1.mutable_value());
     assert(result == MOJO_RESULT_OK);
     handle_to_self.reset(h0);
     handle_to_peer.reset(h1);
   }
 
   typename Interface<S>::ScopedHandle handle_to_self;
   typename Interface<P>::ScopedHandle handle_to_peer;
 };
 
 // TODO(darin): Once we have the ability to use C++11 features, consider
 // defining a template alias for ScopedInterfaceHandle<S>.
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_H_