Adds a way to determine id of content handler that created app

mojo/application/public/cpp/lib/service_registry.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_APPLICATION_PUBLIC_CPP_LIB_SERVICE_REGISTRY_H_
 #define MOJO_APPLICATION_PUBLIC_CPP_LIB_SERVICE_REGISTRY_H_
 
 #include <set>
 #include <string>
 
 #include "mojo/application/public/cpp/application_connection.h"
 #include "mojo/application/public/cpp/lib/service_connector_registry.h"
 #include "mojo/application/public/interfaces/service_provider.mojom.h"
+#include "mojo/application/public/interfaces/shell.mojom.h"
 #include "mojo/public/cpp/bindings/binding.h"
 
 namespace mojo {
 namespace internal {
 
 // A ServiceRegistry represents each half of a connection between two
 // applications, allowing customization of which services are published to the
 // other.
 class ServiceRegistry : public ServiceProvider, public ApplicationConnection {
  public:
   ServiceRegistry();
   // |allowed_interfaces| are the set of interfaces that the shell has allowed
   // an application to expose to another application. If this set contains only
   // the string value "*" all interfaces may be exposed.
   ServiceRegistry(const std::string& connection_url,
                   const std::string& remote_url,
                   ServiceProviderPtr remote_services,
                   InterfaceRequest<ServiceProvider> local_services,
                   const std::set<std::string>& allowed_interfaces);
   ~ServiceRegistry() override;
 
+  Shell::ConnectToApplicationCallback GetConnectToApplicationCallback();
+
   // ApplicationConnection overrides.
   void SetServiceConnector(ServiceConnector* service_connector) override;
   bool SetServiceConnectorForName(ServiceConnector* service_connector,
                                   const std::string& interface_name) override;
   const std::string& GetConnectionURL() override;
   const std::string& GetRemoteApplicationURL() override;
   ServiceProvider* GetServiceProvider() override;
   ServiceProvider* GetLocalServiceProvider() override;
   void SetRemoteServiceProviderConnectionErrorHandler(
       const Closure& handler) override;
+  bool GetContentHandlerID(uint32_t* target_id) override;
+  void AddContentHandlerIDCallback(const Closure& callback) override;
   base::WeakPtr<ApplicationConnection> GetWeakPtr() override;
 
   void RemoveServiceConnectorForName(const std::string& interface_name);
 
  private:
+  void OnGotContentHandlerID(uint32_t content_handler_id);
+
   // ServiceProvider method.
   void ConnectToService(const mojo::String& service_name,
                         ScopedMessagePipeHandle client_handle) override;
 
   const std::string connection_url_;
   const std::string remote_url_;
   Binding<ServiceProvider> local_binding_;
   ServiceProviderPtr remote_service_provider_;
   ServiceConnectorRegistry service_connector_registry_;
   const std::set<std::string> allowed_interfaces_;
   const bool allow_all_interfaces_;
-  base::WeakPtrFactory<ApplicationConnection> weak_factory_;
+  // The id of the content_handler is only available once the callback from
+  // establishing the connection is made.
+  uint32_t content_handler_id_;
+  bool is_content_handler_id_valid_;
+  std::vector<Closure> content_handler_id_callbacks_;
+  base::WeakPtrFactory<ServiceRegistry> weak_factory_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(ServiceRegistry);
 };
 
 }  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_APPLICATION_PUBLIC_CPP_LIB_SERVICE_REGISTRY_H_