Add a ServiceRegistry::ConnectToRemoteService that takes an InterfaceRequest<>.

chrome/browser/process_resource_usage.h

 // Copyright 2015 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 CHROME_BROWSER_PROCESS_RESOURCE_USAGE_H_
 #define CHROME_BROWSER_PROCESS_RESOURCE_USAGE_H_
 
 #include "base/basictypes.h"
 #include "base/threading/thread_checker.h"
 #include "chrome/common/resource_usage_reporter.mojom.h"
 
 // Provides resource usage information about a child process.
 //
 // This is a wrapper around the ResourceUsageReporter Mojo service that exposes
 // information about resources used by a child process. Currently, this is only
 // V8 memory usage, but could be expanded to include other resources such as web
 // cache. This is intended for status viewers such as the task manager and
 // about://memory-internals.
 //
 // To create:
-// 1. Obtain a ResourceUsageReporter connection using the child process's
-//    service registry. i.e:
-//    ResourceUsageReporterPtr service;
-//    process->GetServiceRegistry()->ConnectToRemoteService(&service);
-// 2. If needed, the connection can be passed to another thread using
-//    ResourceUsageReporterPtr::PassInterface().
-// 3. Pass the service to the constructor.
+// 1. Create a ResourceUsageReporterPtr and obtain an InterfaceRequest<> using
+//    mojo::GetProxy.
+// 2. Use the child process's service registry to connect to the service using
+//    the InterfaceRequest<>. Note, ServiceRegistry is thread hostile and
+//    must always be accessed from the same thread. However, InterfaceRequest<>
+//    can be passed safely between threads, and therefore a task can be posted
+//    to the ServiceRegistry thread to connect to the remote service.
+// 3. Pass the ResourceUsageReporterPtr to the constructor.
+//
+// Example:
+//   void Foo::ConnectToService(
+//       mojo::InterfaceRequest<ResourceUsageReporter> req) {
+//     content::ServiceRegistry* registry = host_->GetServiceRegistry();
+//     registry->ConnectToRemoteService(req.Pass());
+//   }
+//
+//   ...
+//     ResourceUsageReporterPtr service;
+//     mojo::InterfaceRequest<ResourceUsageReporter> request =
+//         mojo::GetProxy(&service);
+//     content::BrowserThread::PostTask(
+//         content::BrowserThread::IO, FROM_HERE,
+//         base::Bind(&Foo::ConnectToService, this, base::Passed(&request)));
+//     resource_usage_.reset(new ProcessResourceUsage(service.Pass()));
+//   ...
 //
 // Note: ProcessResourceUsage is thread-hostile and must live on a single
 // thread.
 class ProcessResourceUsage {
  public:
   // Must be called from the same thread that created |service|.
   explicit ProcessResourceUsage(ResourceUsageReporterPtr service);
   ~ProcessResourceUsage();
 
   // Refresh the resource usage information.
@@ skipping 12 matching lines @@
   bool update_in_progress_;
 
   ResourceUsageDataPtr stats_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(ProcessResourceUsage);
 };
 
 #endif  // CHROME_BROWSER_PROCESS_RESOURCE_USAGE_H_