service worker: Tweak some documentation.

content/browser/service_worker/embedded_worker_registry.cc

 // 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.
 
 #include "content/browser/service_worker/embedded_worker_registry.h"
 
 #include "base/bind_helpers.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/stl_util.h"
 #include "content/browser/renderer_host/render_widget_helper.h"
@@ skipping 238 matching lines @@
     int process_id) {
   if (!context_)
     return SERVICE_WORKER_ERROR_ABORT;
 
   // The ServiceWorkerDispatcherHost is supposed to be created when the process
   // is created, and keep an entry in process_sender_map_ for its whole
   // lifetime.
   DCHECK(ContainsKey(process_sender_map_, process_id));
 
   int embedded_worker_id = params->embedded_worker_id;
+#ifndef NDEBUG

[nhiroki, 2016/07/19 03:37:53]

"#if DCHECK_IS_ON()" would be better for DCHECK_ALWAYS_ON

[falken, 2016/07/22 01:34:47]

Acknowledged.

+  // Assert the embedded worker's process id is |process_id|.
   WorkerInstanceMap::iterator found = worker_map_.find(embedded_worker_id);
   DCHECK(found != worker_map_.end());
   DCHECK_EQ(found->second->process_id(), process_id);

[nhiroki, 2016/07/19 03:37:53]

Optional: I'd prefer not to have macros in a production code as much as possible
in terms of readability. With following code, we could avoid them:

DCHECK(GetWorker(embedded_worker_id));
DCHECK_EQ(GetWorker(embedded_worker_id)->process_id(), process_id);

[falken, 2016/07/22 01:34:47]

Much better, done.

-
+  // Assert the embedded worker is not in the map for starting/running workers.
   DCHECK(!ContainsKey(worker_process_map_, process_id) ||
          worker_process_map_[process_id].count(embedded_worker_id) == 0);

[nhiroki, 2016/07/19 03:37:53]

Optional: "!ContainsKey(worker_process_map_[process_id], embedded_worker_id)"
would be consistent with the former expression.

[falken, 2016/07/22 01:34:47]

Huh yea. Not sure why I used count in the first place.

+#endif  // NDEBUG
 
   ServiceWorkerStatusCode status =
       Send(process_id, new EmbeddedWorkerMsg_StartWorker(*params));
   if (status == SERVICE_WORKER_OK)
     worker_process_map_[process_id].insert(embedded_worker_id);
   return status;
 }
 
 ServiceWorkerStatusCode EmbeddedWorkerRegistry::Send(
     int process_id, IPC::Message* message_ptr) {
@@ skipping 25 matching lines @@
   EmbeddedWorkerInstance* worker = GetWorker(embedded_worker_id);
   if (!worker || worker->process_id() != process_id) {
     UMA_HISTOGRAM_BOOLEAN("ServiceWorker.WorkerForMessageFound", false);
     return nullptr;
   }
   UMA_HISTOGRAM_BOOLEAN("ServiceWorker.WorkerForMessageFound", true);
   return worker;
 }
 
 }  // namespace content