Service Manager: Rework Service and ServiceContext lifetime

content/common/service_manager/embedded_service_runner.h

 // Copyright 2016 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 CONTENT_COMMON_SERVICE_MANAGER_EMBEDDED_SERVICE_RUNNER_H_
 #define CONTENT_COMMON_SERVICE_MANAGER_EMBEDDED_SERVICE_RUNNER_H_
 
 #include <memory>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_piece.h"
 #include "content/public/common/service_info.h"
 #include "services/service_manager/public/cpp/service.h"
 #include "services/service_manager/public/interfaces/service.mojom.h"
 
 namespace content {
 
-// Hosts an in-process service instance that supports multiple Service
-// connections. The first incoming connection will invoke a provided factory
-// function to instantiate the service, and the service will automatically be
-// torn down when its last connection is lost. The service may be launched and
-// torn down multiple times by a single EmbeddedServiceRunner instance.
+// Hosts in-process service instances for a given service.
 class EmbeddedServiceRunner {
  public:
-  // Constructs a runner which hosts a service. If an existing instance of the
-  // service is not running when an incoming connection is made, details from
-  // |info| will be used to construct a new instance.
+  // Constructs a runner for a service. Every new instance started by the
+  // Service Manager for this service will invoke the factory function on |info|
+  // to create a new concrete instance of the Service implementation.
   EmbeddedServiceRunner(const base::StringPiece& name,
                         const ServiceInfo& info);
   ~EmbeddedServiceRunner();
 
-  // Binds an incoming ServiceRequest for this service. If the service isn't
-  // already running, it is started. Otherwise the request is bound to the
-  // running instance.
+  // Binds an incoming ServiceRequest for this service. This creates a new
+  // instance of the Service implementation.
   void BindServiceRequest(service_manager::mojom::ServiceRequest request);
 
-  // Sets a callback to run after the service loses its last connection and is
-  // torn down.
+  // Sets a callback to run when all instances of the service have stopped.
   void SetQuitClosure(const base::Closure& quit_closure);
 
  private:
-  class Instance;
+  class InstanceManager;
 
   void OnQuit();
 
-  // A reference to the service instance which may operate on the
-  // |task_runner_|'s thread.
-  scoped_refptr<Instance> instance_;
+  // A reference to the instance manager, which may operate on another thread.
+  scoped_refptr<InstanceManager> instance_manager_;
 
   base::Closure quit_closure_;
 
   base::WeakPtrFactory<EmbeddedServiceRunner> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(EmbeddedServiceRunner);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_COMMON_SERVICE_MANAGER_EMBEDDED_SERVICE_RUNNER_H_