[Background Sync] Add renderer code to interface between JS API and back-end service

content/child/background_sync/background_sync_provider_thread_proxy.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/child/background_sync/background_sync_provider_thread_proxy.h"
+
+#include "base/bind.h"
+#include "base/bind_helpers.h"
+#include "base/lazy_instance.h"
+#include "base/location.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/single_thread_task_runner.h"
+#include "base/threading/thread_local.h"
+#include "content/child/background_sync/background_sync_provider.h"
+
+using base::LazyInstance;
+using base::ThreadLocalPointer;
+
+namespace content {
+
+namespace {
+
+// CallbackThreadAdapter<S,T> is a wrapper for WebCallbacks<S,T> which
+// switches to a specific thread before calling the wrapped callback's
+// onSuccess or onError methods.
+//
+// Takes ownership of the WebCallbacks object which it wraps.
+template <typename S, typename T>
+class CallbackThreadAdapter : public blink::WebCallbacks<S, T> {
+ public:
+  CallbackThreadAdapter(scoped_ptr<blink::WebCallbacks<S, T>> callbacks,
+                        int worker_thread_id)
+      : worker_thread_id_(worker_thread_id) {
+    callbacks_.reset(callbacks.release());
+  }
+
+  virtual void onSuccess(S* results) {
+    // If the worker thread has been destroyed, then this task will be
+    // silently discarded.
+    WorkerTaskRunner::Instance()->PostTask(
+        worker_thread_id_,
+        base::Bind(&blink::WebCallbacks<S, T>::onSuccess,
+                   base::Unretained(callbacks_.get()), results));
+  }
+
+  virtual void onError(T* error) {
+    // If the worker thread has been destroyed, then this task will be
+    // silently discarded.
+    WorkerTaskRunner::Instance()->PostTask(
+        worker_thread_id_,
+        base::Bind(&blink::WebCallbacks<S, T>::onError,
+                   base::Unretained(callbacks_.get()), error));
+  }
+
+ private:
+  scoped_ptr<blink::WebCallbacks<S, T>> callbacks_;
+  int worker_thread_id_;
+};
+
+LazyInstance<ThreadLocalPointer<BackgroundSyncProviderThreadProxy>>::Leaky
+    g_sync_provider_tls = LAZY_INSTANCE_INITIALIZER;
+
+}  // anonymous namespace
+
+BackgroundSyncProviderThreadProxy*
+BackgroundSyncProviderThreadProxy::GetThreadInstance(
+    base::SingleThreadTaskRunner* main_thread_task_runner,
+    BackgroundSyncProvider* sync_provider) {
+  if (g_sync_provider_tls.Pointer()->Get())
+    return g_sync_provider_tls.Pointer()->Get();
+
+  BackgroundSyncProviderThreadProxy* instance =
+      new BackgroundSyncProviderThreadProxy(main_thread_task_runner,
+                                            sync_provider);
+  DCHECK(WorkerTaskRunner::Instance()->CurrentWorkerId());
+  WorkerTaskRunner::Instance()->AddStopObserver(instance);
+  return instance;
+}
+
+void BackgroundSyncProviderThreadProxy::registerBackgroundSync(
+    const blink::WebSyncRegistration* options,
+    blink::WebServiceWorkerRegistration* service_worker_registration,
+    blink::WebSyncRegistrationCallbacks* callbacks) {
+  DCHECK(options);
+  DCHECK(service_worker_registration);
+  DCHECK(callbacks);
+  main_thread_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&BackgroundSyncProvider::registerBackgroundSync,
+                 base::Unretained(sync_provider_), options,
+                 service_worker_registration,
+                 new CallbackThreadAdapter<blink::WebSyncRegistration,
+                                           blink::WebSyncError>(
+                     make_scoped_ptr(callbacks),
+                     WorkerTaskRunner::Instance()->CurrentWorkerId())));
+}
+
+void BackgroundSyncProviderThreadProxy::unregisterBackgroundSync(
+    blink::WebSyncRegistration::Periodicity periodicity,
+    int64_t id,
+    const blink::WebString& tag,
+    blink::WebServiceWorkerRegistration* service_worker_registration,
+    blink::WebSyncUnregistrationCallbacks* callbacks) {
+  DCHECK(service_worker_registration);
+  DCHECK(callbacks);
+  main_thread_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&BackgroundSyncProvider::unregisterBackgroundSync,
+                 base::Unretained(sync_provider_), periodicity, id, tag,
+                 service_worker_registration,
+                 new CallbackThreadAdapter<bool, blink::WebSyncError>(
+                     make_scoped_ptr(callbacks),
+                     WorkerTaskRunner::Instance()->CurrentWorkerId())));
+}
+
+void BackgroundSyncProviderThreadProxy::getRegistration(
+    blink::WebSyncRegistration::Periodicity periodicity,
+    const blink::WebString& tag,
+    blink::WebServiceWorkerRegistration* service_worker_registration,
+    blink::WebSyncRegistrationCallbacks* callbacks) {
+  DCHECK(service_worker_registration);
+  DCHECK(callbacks);
+  main_thread_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&BackgroundSyncProvider::getRegistration,
+                 base::Unretained(sync_provider_), periodicity, tag,
+                 service_worker_registration,
+                 new CallbackThreadAdapter<blink::WebSyncRegistration,
+                                           blink::WebSyncError>(
+                     make_scoped_ptr(callbacks),
+                     WorkerTaskRunner::Instance()->CurrentWorkerId())));
+}
+
+void BackgroundSyncProviderThreadProxy::getRegistrations(
+    blink::WebSyncRegistration::Periodicity periodicity,
+    blink::WebServiceWorkerRegistration* service_worker_registration,
+    blink::WebSyncGetRegistrationsCallbacks* callbacks) {
+  DCHECK(service_worker_registration);
+  DCHECK(callbacks);
+  main_thread_task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&BackgroundSyncProvider::getRegistrations,
+                 base::Unretained(sync_provider_), periodicity,
+                 service_worker_registration,
+                 new CallbackThreadAdapter<
+                     blink::WebVector<blink::WebSyncRegistration*>,
+                     blink::WebSyncError>(
+                     make_scoped_ptr(callbacks),
+                     WorkerTaskRunner::Instance()->CurrentWorkerId())));
+}
+
+void BackgroundSyncProviderThreadProxy::OnWorkerRunLoopStopped() {
+  delete this;
+}
+
+BackgroundSyncProviderThreadProxy::BackgroundSyncProviderThreadProxy(
+    base::SingleThreadTaskRunner* main_thread_task_runner,
+    BackgroundSyncProvider* sync_provider)
+    : main_thread_task_runner_(main_thread_task_runner),
+      sync_provider_(sync_provider) {
+  g_sync_provider_tls.Pointer()->Set(this);
+}
+
+BackgroundSyncProviderThreadProxy::~BackgroundSyncProviderThreadProxy() {
+  g_sync_provider_tls.Pointer()->Set(nullptr);
+}
+
+}  // namespace content