[ServiceWorker] Add EmbeddedWorkerInstanceHost Interface.

content/common/service_worker/embedded_worker.mojom

 // 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.
 
 module content.mojom;
 
 import "content/common/service_worker/service_worker_event_dispatcher.mojom";
+import "mojo/common/string16.mojom";
 import "services/service_manager/public/interfaces/interface_provider.mojom";
 import "third_party/WebKit/public/web/console_message.mojom";
 import "url/mojo/url.mojom";
 
 [Native]
 struct EmbeddedWorkerStartParams;
 
-// Interface to control a renderer-side worker's environment.
+// Interface to control a renderer-side embedded worker. The browser uses this
+// interface to start, stop, and issue commands to the worker.
 interface EmbeddedWorkerInstanceClient {
   StartWorker(EmbeddedWorkerStartParams params,
-              ServiceWorkerEventDispatcher& dispatcher_request);
-  StopWorker() => ();
+              ServiceWorkerEventDispatcher& dispatcher_request,
+              associated EmbeddedWorkerInstanceHost instance_host);
+  // The response is sent back via EmbeddedWorkerInstanceHost.OnStopped().
+  StopWorker();
   ResumeAfterDownload();
   AddMessageToConsole(blink.mojom.ConsoleMessageLevel level,
                       string message);
-};
+};
+
+// Interface to control a browser-side embedded worker instance. The renderer
+// uses this interface to report embedded worker state back to the browser.
+// This interface is associated with the EmbeddedWorkerInstanceClient interface.
+interface EmbeddedWorkerInstanceHost {
+  // Sent on main thread.

[falken, 2017/04/11 14:27:36]

I'm curious why it's important to document sent on main thread vs worker thread.
Is it just describing the current code, or a warning that you shouldn't call the
function from the wrong thread?

Where is it defined which thread on the receiver the function is called on? Is
it always the IO thread for these mojo functions? Is it valuable to document
that, or is it obvious?

[leonhsl(Using Gerrit), 2017/04/12 03:34:04]

Acknowledged.

[leonhsl(Using Gerrit), 2017/04/12 12:32:12]

Yes 'sent on xxx thread' is just describing the current code, so I removed them
from this mojom file. And also added comments into embedded_worker_instance.h
saying that all implementation functions run on browser IO thread.

+  // Indicates that the worker is ready for inspection.
+  OnReadyForInspection();
+  // Indicates that the worker has loaded the script.
+  OnScriptLoaded();
+  // Indicates that the worker has failed to load the script.
+  OnScriptLoadFailed();
+  // Indicates that the worker is stopped.

[falken, 2017/04/11 14:27:36]

nit: just "that the worker stopped"

[leonhsl(Using Gerrit), 2017/04/12 03:34:04]

Acknowledged.

[leonhsl(Using Gerrit), 2017/04/12 12:32:12]

Done.

+  OnStopped();
+
+  // Sent on worker thread.
+  // Indicates that the worker thread is started. |thread_id| is the actual
+  // platform thread id on which the worker runs, while |provider_id| is the id
+  // of each ServiceWorkerNetworkProvider instance, which is unique in one
+  // renderer process, and the browser process uses this id to maintain a
+  // counterpart ServiceWorkerProviderHost instance.
+  OnThreadStarted(int32 thread_id, int32 provider_id);
+  // Indicates that the worker has evaluated the script. |success| means
+  // evaluating the script completed and no uncaught exception occurred.
+  OnScriptEvaluated(bool success);
+  // Indicates that the worker is started.

[falken, 2017/04/11 14:27:36]

nit: just "that the worker started"

[leonhsl(Using Gerrit), 2017/04/12 03:34:04]

Acknowledged.

[leonhsl(Using Gerrit), 2017/04/12 12:32:12]

Done.

+  OnStarted();
+  // Reports an exception.
+  OnReportException(mojo.common.mojom.String16 error_message, int32 line_number,
+                    int32 column_number, url.mojom.Url source_url);
+  // Reports console message.
+  OnReportConsoleMessage(int32 source_identifier, int32 message_level,
+                         mojo.common.mojom.String16 message, int32 line_number,
+                         url.mojom.Url source_url);
+};