Add LargeIconCache and LargeIconServiceFactory for iOS.

ios/chrome/browser/favicon/large_icon_cache.h

Index: ios/chrome/browser/favicon/large_icon_cache.h
diff --git a/ios/chrome/browser/favicon/large_icon_cache.h b/ios/chrome/browser/favicon/large_icon_cache.h
new file mode 100644
index 0000000000000000000000000000000000000000..67abec9d7c796ed04964bd35f99505129bb34cb0
--- /dev/null
+++ b/ios/chrome/browser/favicon/large_icon_cache.h
@@ -0,0 +1,55 @@
+// 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 {

[noyau (Ping after 24h), 2015/10/30 23:22:31]

I would expect some tests for this class.

[justincohen, 2015/10/31 03:54:21]

I will add this in a followup CL.

+ 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_;

[noyau (Ping after 24h), 2015/10/30 23:22:31]

You cache all those images in memory? From our experience doing tiled image on
bookmarks, keeping the cache on disk was sufficient: The costly bits where the
image manipulations (resizes, filters...). Once it is a bitmap of the right size
loading asynchronously is barely perceptible by the user.

[justincohen, 2015/10/31 03:54:21]

The NTP slide-in animation needs the images loaded synchronously.  Also, it took
upwards of 200ms to load all the favicons on an iPhone 6s.

+
+  DISALLOW_COPY_AND_ASSIGN(LargeIconCache);
+};
+
+#endif  // IOS_CHROME_BROWSER_FAVICON_LARGE_ICON_CACHE_H_