Create ServiceWorkerProviderHost before starting worker

content/browser/service_worker/embedded_worker_instance.h

 // Copyright 2013 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_BROWSER_SERVICE_WORKER_EMBEDDED_WORKER_INSTANCE_H_
 #define CONTENT_BROWSER_SERVICE_WORKER_EMBEDDED_WORKER_INSTANCE_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 210 matching lines @@
 
   // Called back from StartTask after a start worker message is sent.
   void OnStartWorkerMessageSent();
 
   // Implements mojom::EmbeddedWorkerInstanceHost.
   // These functions all run on the IO thread.
   void OnReadyForInspection() override;
   void OnScriptLoaded() override;
   // Notifies the corresponding provider host that the thread has started and is
   // ready to receive messages.
-  void OnThreadStarted(int thread_id, int provider_id) override;
+  void OnThreadStarted(int thread_id) override;
   void OnScriptLoadFailed() override;
   // Fires the callback passed to Start().
   void OnScriptEvaluated(bool success) override;
   // Changes the internal worker status from STARTING to RUNNING.
   void OnStarted() override;
   // Resets the embedded worker instance to the initial state. This will change
   // the internal status from STARTING or RUNNING to STOPPED.
   void OnStopped() override;
   void OnReportException(const base::string16& error_message,
                          int line_number,
@@ skipping 34 matching lines @@
   const int embedded_worker_id_;
 
   EmbeddedWorkerStatus status_;
   StartingPhase starting_phase_;
   int restart_count_;
 
   // Current running information.
   std::unique_ptr<EmbeddedWorkerInstance::WorkerProcessHandle> process_handle_;
   int thread_id_;
 
-  // |client_| is used to send messages to the renderer process.
+  // |client_| is used to send messages to the renderer process. This should not
+  // disconnected from the browser side manually because the pipe is possible to
+  // be used by other associated interfaces before disconnected from the
+  // renderer side.

[falken, 2017/06/06 14:06:33]

Not sure I understand. Does this mean the browser side should never disconnect
the pipe, and instead it's the renderer's responsibility to disconnect it?

If so, I'd suggest:
"The browser process should not disconnect the pipe, because other associated
interfaces may be using it. The renderer process will disconnect the pipe when
appropriate."

[shimazu, 2017/06/12 06:08:12]

Yes, that's correct. Updated, thanks!

   mojom::EmbeddedWorkerInstanceClientPtr client_;
 
   // Binding for EmbeddedWorkerInstanceHost, runs on IO thread.
   mojo::AssociatedBinding<EmbeddedWorkerInstanceHost> instance_host_binding_;
 
   // TODO(shimazu): Remove this after EmbeddedWorkerStartParams is changed to
   // a mojo struct.
   mojom::ServiceWorkerEventDispatcherRequest pending_dispatcher_request_;
 
   // Whether devtools is attached or not.
@@ skipping 16 matching lines @@
   base::TimeTicks step_time_;
 
   base::WeakPtrFactory<EmbeddedWorkerInstance> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(EmbeddedWorkerInstance);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_SERVICE_WORKER_EMBEDDED_WORKER_INSTANCE_H_