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

chrome/browser/favicon/fallback_icon_service_factory.h

 // 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.
 
-#ifndef CHROME_BROWSER_AUTOCOMPLETE_IN_MEMORY_URL_INDEX_FACTORY_H_
-#define CHROME_BROWSER_AUTOCOMPLETE_IN_MEMORY_URL_INDEX_FACTORY_H_
+#ifndef CHROME_BROWSER_FAVICON_FALLBACK_ICON_SERVICE_FACTORY_H_
+#define CHROME_BROWSER_FAVICON_FALLBACK_ICON_SERVICE_FACTORY_H_
 
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 template <typename T> struct DefaultSingletonTraits;
 
-class InMemoryURLIndex;
-class Profile;
+class FallbackIconService;
 
-class InMemoryURLIndexFactory : public BrowserContextKeyedServiceFactory {
+namespace content {
+class BrowserContext;
+}
+
+// Singleton that owns all FallbackIconService and associates them with
+// BrowserContext instances.
+class FallbackIconServiceFactory : public BrowserContextKeyedServiceFactory {
  public:
-  static InMemoryURLIndex* GetForProfile(Profile* profile);
-  static InMemoryURLIndexFactory* GetInstance();
+  static FallbackIconService* GetForBrowserContext(
+      content::BrowserContext* context);
+
+  static FallbackIconServiceFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<InMemoryURLIndexFactory>;
+  friend struct DefaultSingletonTraits<FallbackIconServiceFactory>;
 
-  InMemoryURLIndexFactory();
-  ~InMemoryURLIndexFactory() override;
+  FallbackIconServiceFactory();
+  ~FallbackIconServiceFactory() override;
 
   // BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* context) const override;
-  content::BrowserContext* GetBrowserContextToUse(
-      content::BrowserContext* context) const override;
   bool ServiceIsNULLWhileTesting() const override;
+
+  DISALLOW_COPY_AND_ASSIGN(FallbackIconServiceFactory);
 };
 
-#endif  // CHROME_BROWSER_AUTOCOMPLETE_IN_MEMORY_URL_INDEX_FACTORY_H_
+#endif  // CHROME_BROWSER_FAVICON_FALLBACK_ICON_SERVICE_FACTORY_H_