[Fallback Icons] Refactor FallbackIconService to be a BrowserContext-level singleton

chrome/browser/favicon/fallback_icon_service_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 "chrome/browser/favicon/fallback_icon_service_factory.h"
+
+#include "base/memory/singleton.h"
+#include "base/prefs/pref_service.h"
+#include "chrome/browser/favicon/chrome_fallback_icon_client_factory.h"
+#include "chrome/browser/history/history_service.h"
+#include "chrome/browser/history/history_service_factory.h"
+#include "chrome/browser/profiles/profile.h"
+#include "components/favicon_base/fallback_icon_service.h"
+#include "components/keyed_service/content/browser_context_dependency_manager.h"
+
+// static
+favicon_base::FallbackIconService* FallbackIconServiceFactory::GetForProfile(
+    Profile* profile, ServiceAccessType sat) {
+  if (!profile->IsOffTheRecord()) {
+    return static_cast<favicon_base::FallbackIconService*>(
+        GetInstance()->GetServiceForBrowserContext(profile, true));
+  } else if (sat == ServiceAccessType::EXPLICIT_ACCESS) {
+    // Profile must be OffTheRecord in this case.
+    return static_cast<favicon_base::FallbackIconService*>(
+        GetInstance()->GetServiceForBrowserContext(
+            profile->GetOriginalProfile(), true));
+  }
+
+  // Profile is OffTheRecord without access.
+  NOTREACHED() << "This profile is OffTheRecord";
+  return NULL;
+}
+
+// static
+FallbackIconServiceFactory* FallbackIconServiceFactory::GetInstance() {
+  return Singleton<FallbackIconServiceFactory>::get();
+}
+
+FallbackIconServiceFactory::FallbackIconServiceFactory()
+    : BrowserContextKeyedServiceFactory(
+        "FallbackIconService",
+        BrowserContextDependencyManager::GetInstance()) {
+  DependsOn(HistoryServiceFactory::GetInstance());
+  DependsOn(ChromeFallbackIconClientFactory::GetInstance());
+}
+
+FallbackIconServiceFactory::~FallbackIconServiceFactory() {}
+
+KeyedService* FallbackIconServiceFactory::BuildServiceInstanceFor(
+    content::BrowserContext* profile) const {
+  FallbackIconClient* fallback_icon_client =
+      ChromeFallbackIconClientFactory::GetForProfile(
+          static_cast<Profile*>(profile));
+  return new favicon_base::FallbackIconService(fallback_icon_client);
+}
+
+bool FallbackIconServiceFactory::ServiceIsNULLWhileTesting() const {
+  return true;
+}