Modify bindings to enforce that an error handler callback is only set after binding to a msg pipe.

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 <assert.h>
 
 #include "mojo/public/c/environment/async_waiter.h"
@@ skipping 30 matching lines @@
 //     void Create(..., InterfaceRequest<Foo> request) override {
 //       new StronglyBound(request.Pass());  // The binding now owns the
 //                                           // instance of StronglyBound.
 //     }
 //   };
 template <typename Interface>
 class StrongBinding {
   MOJO_MOVE_ONLY_TYPE(StrongBinding)
 
  public:
-  explicit StrongBinding(Interface* impl) : binding_(impl) {
-    binding_.set_connection_error_handler([this]() { OnConnectionError(); });
-  }
+  explicit StrongBinding(Interface* impl) : binding_(impl) {}
 
   StrongBinding(
       Interface* impl,
       ScopedMessagePipeHandle handle,
       const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter())
       : StrongBinding(impl) {
-    binding_.Bind(handle.Pass(), waiter);
+    Bind(handle.Pass(), waiter);
   }
 
   StrongBinding(
       Interface* impl,
       InterfacePtr<Interface>* ptr,
       const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter())
       : StrongBinding(impl) {
-    binding_.Bind(ptr, waiter);
+    Bind(ptr, waiter);
   }
 
   StrongBinding(
       Interface* impl,
       InterfaceRequest<Interface> request,
       const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter())
       : StrongBinding(impl) {
-    binding_.Bind(request.Pass(), waiter);
+    Bind(request.Pass(), waiter);
   }
 
   ~StrongBinding() {}
 
   void Bind(
       ScopedMessagePipeHandle handle,
       const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter()) {
     assert(!binding_.is_bound());
     binding_.Bind(handle.Pass(), waiter);
+    binding_.set_connection_error_handler([this]() { OnConnectionError(); });
   }
 
   void Bind(
       InterfacePtr<Interface>* ptr,
       const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter()) {
     assert(!binding_.is_bound());
     binding_.Bind(ptr, waiter);
+    binding_.set_connection_error_handler([this]() { OnConnectionError(); });
   }
 
   void Bind(
       InterfaceRequest<Interface> request,
       const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter()) {
     assert(!binding_.is_bound());
     binding_.Bind(request.Pass(), waiter);
+    binding_.set_connection_error_handler([this]() { OnConnectionError(); });
   }
 
   bool WaitForIncomingMethodCall() {
     return binding_.WaitForIncomingMethodCall();
   }
 
   // Note: The error handler must not delete the interface implementation.
+  //
+  // This method may only be called after this StrongBinding has been bound to a
+  // message pipe.
   void set_connection_error_handler(const Closure& error_handler) {
+    assert(binding_.is_bound());
     connection_error_handler_ = error_handler;
   }
 
   Interface* impl() { return binding_.impl(); }
   // Exposed for testing, should not generally be used.
   internal::Router* internal_router() { return binding_.internal_router(); }
 
   void OnConnectionError() {
     connection_error_handler_.Run();
     delete binding_.impl();
   }
 
  private:
   Closure connection_error_handler_;
   Binding<Interface> binding_;
 };
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_STRONG_BINDING_H_