ServiceWorker: Make start worker sequence cancelable

content/browser/service_worker/service_worker_process_manager.cc

 // Copyright 2014 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/service_worker_process_manager.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <utility>
@@ skipping 216 matching lines @@
   }
 
   if (IsShutdown()) {
     // Shutdown already released all instances.
     DCHECK(instance_info_.empty());
     return;
   }
 
   std::map<int, ProcessInfo>::iterator info =
       instance_info_.find(embedded_worker_id);
-  // TODO(nhiroki): Make sure the instance info is not mixed up.
-  // (http://crbug.com/568915)
-  CHECK(info != instance_info_.end());
+  // ReleaseWorkerProcess could be called for a nonexistent worker id, for
+  // example, when request to start a worker is aborted on the IO thread during
+  // process allocation that is failed on the UI thread.
+  if (info == instance_info_.end())
+    return;
 
   RenderProcessHost* rph = NULL;
   if (info->second.site_instance.get()) {
     rph = info->second.site_instance->GetProcess();
     DCHECK_EQ(info->second.process_id, rph->GetID())
         << "A SiteInstance's process shouldn't get destroyed while we're "
            "holding a reference to it. Was the reference actually held?";
   } else {
     rph = RenderProcessHost::FromID(info->second.process_id);
     DCHECK(rph)
@@ skipping 54 matching lines @@
 namespace std {
 // Destroying ServiceWorkerProcessManagers only on the UI thread allows the
 // member WeakPtr to safely guard the object's lifetime when used on that
 // thread.
 void default_delete<content::ServiceWorkerProcessManager>::operator()(
     content::ServiceWorkerProcessManager* ptr) const {
   content::BrowserThread::DeleteSoon(
       content::BrowserThread::UI, FROM_HERE, ptr);
 }
 }  // namespace std