Add mojo::Binding<Interface> for more flexible pipe<->impl binding

mojo/public/cpp/bindings/strong_connector.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_STRONG_CONNECTOR_H_
+#define MOJO_PUBLIC_CPP_BINDINGS_STRONG_CONNECTOR_H_
+
+#include "mojo/public/c/environment/async_waiter.h"
+#include "mojo/public/cpp/bindings/connector.h"
+#include "mojo/public/cpp/bindings/error_handler.h"
+#include "mojo/public/cpp/bindings/lib/filter_chain.h"
+#include "mojo/public/cpp/bindings/lib/message_header_validator.h"
+#include "mojo/public/cpp/bindings/lib/router.h"
+#include "mojo/public/cpp/system/core.h"
+
+namespace mojo {
+
+// This connects an interface implementation strongly to a pipe. When a
+// connection error is detected the implementation is deleted. Deleting the
+// connector also closes the pipe.
+//
+// Example of an implementation that is always bound strongly to a pipe
+//
+//   class StronglyBound : public Foo {
+//    public:
+//     explicit StronglyBound(ScopedMessagePipeHandle handle)
+//         : connector_(this, handle.Pass()) {}
+//
+//     // Foo implementation here
+//
+//    private:
+//     StrongConnector<Foo> connector_;
+//   };
+//
+template <typename Interface>
+class StrongConnector : public Connector<Interface> {
+ public:
+  explicit StrongConnector(Interface* impl) : Connector<Interface>(impl) {}
+
+  StrongConnector(
+      Interface* impl,
+      ScopedMessagePipeHandle handle,
+      const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter())
+      : Connector<Interface>(impl, handle.Pass(), waiter) {}
+
+  virtual ~StrongConnector() {}
+
+  // ErrorHandler implementation
+  void OnConnectionError() override {
+    Connector<Interface>::OnConnectionError();
+    delete this->impl();
+  }
+};
+
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_CPP_BINDINGS_STRONG_CONNECTOR_H_