Add LargeIconCache and LargeIconServiceFactory for iOS.

ios/chrome/browser/favicon/large_icon_cache.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 IOS_CHROME_BROWSER_FAVICON_LARGE_ICON_CACHE_H_
+#define IOS_CHROME_BROWSER_FAVICON_LARGE_ICON_CACHE_H_
+
+#include "base/containers/mru_cache.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "components/keyed_service/core/keyed_service.h"
+
+class GURL;
+struct LargeIconCacheEntry;
+
+namespace favicon_base {
+struct LargeIconResult;
+}
+
+namespace ios {
+class ChromeBrowserState;
+}
+
+// Provides a cache of most recently used LargeIconResult.
+//
+// Example usage:
+//   LargeIconCache* large_icon_cache =
+//       IOSChromeLargeIconServiceFactory::GetForBrowserState(browser_state);
+//   scoped_ptr<favicon_base::LargeIconResult> icon =
+//       large_icon_cache->GetCachedResult(...);
+//
+class LargeIconCache : public KeyedService {
+ public:
+  LargeIconCache();
+  ~LargeIconCache() override;
+
+  // |LargeIconService| does everything on callbacks, and iOS needs to load the
+  // icons immediately on page load. This caches the LargeIconResult so we can
+  // immediately load.
+  void SetCachedResult(const GURL& url, const favicon_base::LargeIconResult&);
+
+  // Returns a cached LargeIconResult.
+  scoped_ptr<favicon_base::LargeIconResult> GetCachedResult(const GURL& url);
+
+ private:
+  // Clones a LargeIconResult.
+  scoped_ptr<favicon_base::LargeIconResult> CloneLargeIconResult(
+      const favicon_base::LargeIconResult& large_icon_result);
+
+  base::OwningMRUCache<GURL, LargeIconCacheEntry*> cache_;
+
+  DISALLOW_COPY_AND_ASSIGN(LargeIconCache);
+};
+
+#endif  // IOS_CHROME_BROWSER_FAVICON_LARGE_ICON_CACHE_H_