[ServiceWorkerCache] Serialize ServiceWorkerCacheStorage operations

content/browser/service_worker/service_worker_cache_scheduler.cc

+// Copyright 2015 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_cache_scheduler.h"
+
+#include <string>
+
+#include "base/logging.h"
+
+namespace content {
+
+ServiceWorkerCacheScheduler::ServiceWorkerCacheScheduler()
+    : operation_running_(false) {
+}
+
+ServiceWorkerCacheScheduler::~ServiceWorkerCacheScheduler() {
+}
+
+void ServiceWorkerCacheScheduler::ScheduleOperation(
+    const base::Closure& closure) {
+  pending_operations_.push_back(closure);
+  RunOperationIfIdle();
+}
+
+void ServiceWorkerCacheScheduler::CompleteOperationAndRunNext() {
+  DCHECK(!pending_operations_.empty());
+  operation_running_ = false;
+  pending_operations_.pop_front();
+  RunOperationIfIdle();
+}
+
+bool ServiceWorkerCacheScheduler::Empty() const {
+  return pending_operations_.empty();
+}
+
+void ServiceWorkerCacheScheduler::RunOperationIfIdle() {
+  DCHECK(!operation_running_ || !pending_operations_.empty());
+
+  if (!operation_running_ && !pending_operations_.empty()) {
+    operation_running_ = true;
+    // TODO(jkarlin): Run multiple operations in parallel where allowed.
+    pending_operations_.front().Run();
+  }
+}
+
+}  // namespace content