Remove the MessageLoop::DestructionObserver from mojo bindings.

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 <memory>
 #include <string>
 #include <utility>
@@ skipping 13 matching lines @@
 
 namespace mojo {
 
 template <typename Interface>
 class StrongBinding;
 
 template <typename Interface>
 using StrongBindingPtr = base::WeakPtr<StrongBinding<Interface>>;
 
 // This connects an interface implementation strongly to a pipe. When a
-// connection error is detected the implementation is deleted.
+// connection error is detected the implementation is deleted. If the task
+// runner that a StrongBinding is bound on is stopped, the connection error
+// handler will not be invoked and the implementation will not be deleted.
 //
 // To use, call StrongBinding<T>::Create() (see below) or the helper
 // MakeStrongBinding function:
 //
 //   mojo::MakeStrongBinding(base::MakeUnique<FooImpl>(),
 //                           std::move(foo_request));
 //
 template <typename Interface>
 class StrongBinding {
  public:
@@ skipping 69 matching lines @@
 template <typename Interface, typename Impl>
 StrongBindingPtr<Interface> MakeStrongBinding(
     std::unique_ptr<Impl> impl,
     InterfaceRequest<Interface> request) {
   return StrongBinding<Interface>::Create(std::move(impl), std::move(request));
 }
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_STRONG_BINDING_H_