[GCM] Reland: Introduce GCMClientFactory to create GCMClient for GCMProfileService

chrome/browser/services/gcm/gcm_client_factory.cc

+// Copyright (c) 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 "chrome/browser/services/gcm/gcm_client_factory.h"
+
+#include "base/files/file_path.h"
+#include "base/lazy_instance.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "content/public/browser/browser_thread.h"
+#include "google_apis/gcm/gcm_client_impl.h"
+
+namespace gcm {
+
+namespace {
+
+static base::LazyInstance<GCMClientImpl>::Leaky g_gcm_client =
+    LAZY_INSTANCE_INITIALIZER;
+static bool g_gcm_client_initialized = false;
+static GCMClientFactory::TestingFactoryFunction g_gcm_client_factory = NULL;
+static GCMClient* g_gcm_client_override = NULL;
+
+}  // namespace
+
+
+// static
+GCMClient* GCMClientFactory::GetClient() {
+  if (g_gcm_client_override)
+    return g_gcm_client_override;
+  if (g_gcm_client_factory) {
+    g_gcm_client_override = g_gcm_client_factory();
+    return g_gcm_client_override;
+  }
+
+  GCMClientImpl* client = g_gcm_client.Pointer();

[Nicolas Zea, 2014/01/16 23:47:36]

The GCM client expects to live on the IO thread. Does this enforce that?

[jianli, 2014/01/17 00:43:54]

GCMClientFactory::GetClient is expected to be called from IO thread. Added a
DCHECK for it.

+  if (!g_gcm_client_initialized) {
+    // TODO(jianli): get gcm store path.
+    base::FilePath gcm_store_path;
+    scoped_refptr<base::SequencedWorkerPool> worker_pool(
+        content::BrowserThread::GetBlockingPool());
+    scoped_refptr<base::SequencedTaskRunner> blocking_task_runner(
+        worker_pool->GetSequencedTaskRunnerWithShutdownBehavior(
+            worker_pool->GetSequenceToken(),
+            base::SequencedWorkerPool::SKIP_ON_SHUTDOWN));
+    client->Initialize(gcm_store_path, blocking_task_runner);
+    g_gcm_client_initialized = true;
+  }
+  return client;
+}
+
+// static
+void GCMClientFactory::SetTestingFactory(TestingFactoryFunction factory) {
+  if (g_gcm_client_override) {
+    delete g_gcm_client_override;
+    g_gcm_client_override = NULL;
+  }
+  g_gcm_client_factory = factory;
+}
+
+GCMClientFactory::GCMClientFactory() {
+}
+
+GCMClientFactory::~GCMClientFactory() {
+}
+
+}  // namespace gcm