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

mojo/public/cpp/bindings/strong_binding.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_BINDING_H_
+#define MOJO_PUBLIC_CPP_BINDINGS_STRONG_BINDING_H_
+
+#include "mojo/public/c/environment/async_waiter.h"
+#include "mojo/public/cpp/bindings/binding.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)
+//         : binding_(this, handle.Pass()) {}
+//
+//     // Foo implementation here
+//
+//    private:
+//     StrongBinding<Foo> binding_;
+//   };
+//
+template <typename Interface>
+class StrongBinding : public ErrorHandler {
+ public:
+  explicit StrongBinding(Interface* impl) : binding_(impl) {
+    binding_.set_error_handler(this);
+  }
+
+  StrongBinding(
+      Interface* impl,
+      ScopedMessagePipeHandle handle,
+      const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter())
+      : StrongBinding(impl) {
+    binding_.Bind(handle.Pass(), waiter);
+  }
+
+  StrongBinding(
+      Interface* impl,
+      InterfacePtr<Interface>* ptr,
+      const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter())
+      : StrongBinding(impl) {
+    binding_.Bind(ptr, waiter);
+  }
+
+  ~StrongBinding() override {}
+
+  bool WaitForIncomingMethodCall() { binding_.WaitForIncomingMethodCall(); }
+
+  void set_error_handler(ErrorHandler* error_handler) {
+    error_handler_ = error_handler;
+  }
+
+  typename Interface::Client* client() { return binding_.client(); }
+  // Exposed for testing, should not generally be used.
+  internal::Router* router() { return binding_.router(); }
+
+  // ErrorHandler implementation
+  void OnConnectionError() override {
+    if (error_handler_)
+      error_handler_->OnConnectionError();
+    delete binding_.impl();
+  }
+
+ private:
+  ErrorHandler* error_handler_ = nullptr;
+  Binding<Interface> binding_;
+};
+
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_CPP_BINDINGS_STRONG_BINDING_H_