Expose NavigatorHost via Embed() rather than globally.

mojo/public/cpp/application/lazy_interface_ptr.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_APPLICATION_LAZY_INTERFACE_PTR_H_
 #define MOJO_PUBLIC_CPP_APPLICATION_LAZY_INTERFACE_PTR_H_
 
 #include <string>
 
 #include "mojo/public/cpp/application/connect.h"
 #include "mojo/public/interfaces/application/service_provider.mojom.h"
 
 namespace mojo {
 
 template<typename Interface>
 class LazyInterfacePtr : InterfacePtr<Interface> {
  public:
+  LazyInterfacePtr() : service_provider_(NULL) {}
+
   LazyInterfacePtr(ServiceProvider* service_provider)
       : service_provider_(service_provider) {
   }
 
+  void set_service_provider(ServiceProvider* service_provider) {

[darin (slow to review), 2014/09/04 23:22:18]

you probably want to make sure InterfacePtr<Interface>::get() would return null,
right? that way someone doesn't try to change the service provider after the
ConnectToService was called.

this method could also be called Initialize. not sure if you want to go there.
it might help re-inforce the idea that it can only be called once, and that it
is an alternative to the 1-arg ctor.

[Aaron Boodman, 2014/09/05 04:22:34]

I decided to just reset the InterfaceProvider when this is called, so that it
can be called multiple times. Does that work for you?

+    DCHECK(!service_provider_);
+    service_provider_ = service_provider;
+  }
+
   Interface* get() const {
     if (!InterfacePtr<Interface>::get()) {
       mojo::ConnectToService<Interface>(
           service_provider_,
           const_cast<LazyInterfacePtr<Interface>*>(this));
     }
     return InterfacePtr<Interface>::get();
   }
   Interface* operator->() const { return get(); }
   Interface& operator*() const { return *get(); }
 
  private:
   ServiceProvider* service_provider_;
 };
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_APPLICATION_LAZY_INTERFACE_PTR_H_