[cast_channel] Make CastSocket not inherit from ApiResource

extensions/browser/api/cast_channel/cast_channel_service_factory.cc

+// Copyright 2017 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 "extensions/browser/api/cast_channel/cast_channel_service_factory.h"
+
+#include "components/keyed_service/content/browser_context_dependency_manager.h"
+#include "extensions/browser/api/cast_channel/cast_channel_service.h"
+
+namespace extensions {
+namespace api {
+namespace cast_channel {
+
+using content::BrowserContext;
+
+namespace {
+
+base::LazyInstance<CastChannelServiceFactory>::DestructorAtExit
+    service_factory = LAZY_INSTANCE_INITIALIZER;
+}  // namespace
+
+// static
+CastChannelService* CastChannelServiceFactory::GetForBrowserContext(
+    BrowserContext* context) {
+  DCHECK(context);
+  // GetServiceForBrowserContext returns a KeyedService hence the static_cast<>
+  // to return a pointer to CastChannelService.
+  return static_cast<CastChannelService*>(
+      service_factory.Get().GetServiceForBrowserContext(context, true));
+}
+
+// static
+CastChannelServiceFactory* CastChannelServiceFactory::GetInstance() {
+  return &service_factory.Get();
+}
+
+CastChannelServiceFactory::CastChannelServiceFactory()
+    : BrowserContextKeyedServiceFactory(
+          "CastChannelService",
+          BrowserContextDependencyManager::GetInstance()) {}
+
+CastChannelServiceFactory::~CastChannelServiceFactory() {}
+
+content::BrowserContext* CastChannelServiceFactory::GetBrowserContextToUse(
+    content::BrowserContext* context) const {
+  return context;

[mark a. foltz, 2017/05/18 19:12:05]

This will return separate services for a normal profile and its incognito
profile.  If we decide to keep this as a profile-keyed service, it would make
sense to return the same instance for incognito (to be consistent with Media
Router).

[zhaobin, 2017/05/24 01:51:40]

Verified that CastChannelAPI has the same browser context instance for both
normal profile and incognito profile. Added a comment to
CastChannelServiceFactory::GetForBrowserContext() function.

[mark a. foltz, 2017/05/24 17:44:10]

Cool :)

+}
+
+KeyedService* CastChannelServiceFactory::BuildServiceInstanceFor(
+    BrowserContext* context) const {
+  return new CastChannelService();
+}
+
+}  // namespace cast_channel
+}  // namespace api
+}  // namespace extensions