Shut down the ServiceWorker system as the browser's shutting down.

content/browser/service_worker/service_worker_process_manager.cc

Index: content/browser/service_worker/service_worker_process_manager.cc
diff --git a/content/browser/service_worker/service_worker_process_manager.cc b/content/browser/service_worker/service_worker_process_manager.cc
index 03c156be4dc064b148ae2077e530768b81d8418d..7395e7b7b7768675ed4d9225df4436e6a6ba5917 100644
--- a/content/browser/service_worker/service_worker_process_manager.cc
+++ b/content/browser/service_worker/service_worker_process_manager.cc
@@ -51,6 +51,14 @@ ServiceWorkerProcessManager::~ServiceWorkerProcessManager() {
 
 void ServiceWorkerProcessManager::Shutdown() {
   browser_context_ = NULL;
+  for (std::map<int, ProcessInfo>::const_iterator it = instance_info_.begin();
+       it != instance_info_.end();
+       ++it) {
+    RenderProcessHost* rph = RenderProcessHost::FromID(it->second.process_id);
+    DCHECK(rph);
+    static_cast<RenderProcessHostImpl*>(rph)->DecrementWorkerRefCount();
+  }
+  instance_info_.clear();
 }
 
 void ServiceWorkerProcessManager::AllocateWorkerProcess(
@@ -147,6 +155,11 @@ void ServiceWorkerProcessManager::ReleaseWorkerProcess(int embedded_worker_id) {
     // RenderProcessHost.
     return;
   }
+  if (browser_context_ == NULL) {
+    // Shutdown already released all instances.
+    DCHECK(instance_info_.empty());
+    return;
+  }
   std::map<int, ProcessInfo>::iterator info =
       instance_info_.find(embedded_worker_id);
   DCHECK(info != instance_info_.end());