Keep track of ServiceWorkerContext's BrowserContext and expose it.

content/browser/service_worker/service_worker_context_core.cc

Index: content/browser/service_worker/service_worker_context_core.cc
diff --git a/content/browser/service_worker/service_worker_context_core.cc b/content/browser/service_worker/service_worker_context_core.cc
index 51baeb650f08c0bd25959a671bb9bc0f35532db9..5df5783ad1793f25f16698e8c6a4d9af5fd8a72f 100644
--- a/content/browser/service_worker/service_worker_context_core.cc
+++ b/content/browser/service_worker/service_worker_context_core.cc
@@ -435,6 +435,10 @@ void ServiceWorkerContextCore::TransferProviderHostIn(
   delete temp;
 }
 
+BrowserContext* ServiceWorkerContextCore::GetBrowserContext() const {
+  return wrapper_->browser_context();
+}
+
 void ServiceWorkerContextCore::OnWorkerStarted(ServiceWorkerVersion* version) {
   if (!observer_list_.get())
     return;
@@ -497,9 +501,7 @@ void ServiceWorkerContextCore::OnReportConsoleMessage(
 }
 
 ServiceWorkerProcessManager* ServiceWorkerContextCore::process_manager() {
-  if (wrapper_)
-    return wrapper_->process_manager();
-  return NULL;
+  return wrapper_->process_manager();
 }
 
 }  // namespace content