Make PrinterProviderAPI a pure interface

extensions/browser/api/printer_provider/printer_provider_api_factory.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 "extensions/browser/api/printer_provider/printer_provider_api_factory.h"
+
+#include "components/keyed_service/content/browser_context_dependency_manager.h"
+#include "extensions/browser/api/printer_provider/printer_provider_api.h"
+#include "extensions/browser/api/printer_provider_internal/printer_provider_internal_api.h"
+#include "extensions/browser/extension_registry_factory.h"
+#include "extensions/browser/extensions_browser_client.h"
+
+namespace {
+
+static base::LazyInstance<extensions::PrinterProviderAPIFactory> g_api_factory =
+    LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+namespace extensions {
+
+// static
+PrinterProviderAPIFactory* PrinterProviderAPIFactory::GetInstance() {
+  return g_api_factory.Pointer();
+}
+
+PrinterProviderAPI* PrinterProviderAPIFactory::GetForBrowserContext(
+    content::BrowserContext* context) {
+  return static_cast<PrinterProviderAPI*>(
+      GetServiceForBrowserContext(context, true));
+}
+
+PrinterProviderAPIFactory::PrinterProviderAPIFactory()
+    : BrowserContextKeyedServiceFactory(
+          "PrinterProviderAPI",
+          BrowserContextDependencyManager::GetInstance()) {
+  DependsOn(ExtensionsBrowserClient::Get()->GetExtensionSystemFactory());
+  DependsOn(PrinterProviderInternalAPI::GetFactoryInstance());
+  DependsOn(ExtensionRegistryFactory::GetInstance());
+}
+
+PrinterProviderAPIFactory::~PrinterProviderAPIFactory() {
+}
+
+KeyedService* PrinterProviderAPIFactory::BuildServiceInstanceFor(
+    content::BrowserContext* context) const {
+  return PrinterProviderAPI::Create(context);
+}
+
+content::BrowserContext* PrinterProviderAPIFactory::GetBrowserContextToUse(
+    content::BrowserContext* context) const {
+  return ExtensionsBrowserClient::Get()->GetOriginalContext(context);
+}
+
+}  // namespace extensions