Extend LargeIconService to fetch missing favicons from a Google server

components/favicon/core/large_icon_service.h

Index: components/favicon/core/large_icon_service.h
diff --git a/components/favicon/core/large_icon_service.h b/components/favicon/core/large_icon_service.h
index 73a2698448c9182cb2ac43fd9e7103ba14ad49f2..8fa2f1451336d3466fe24663e2466c26f6fb8dff 100644
--- a/components/favicon/core/large_icon_service.h
+++ b/components/favicon/core/large_icon_service.h
@@ -18,6 +18,10 @@ namespace base {
 class TaskRunner;
 }
 
+namespace image_fetcher {
+class ImageFetcher;
+}
+
 namespace favicon {
 
 class FaviconService;
@@ -28,7 +32,8 @@ class LargeIconService : public KeyedService {
  public:
   LargeIconService(
       FaviconService* favicon_service,
-      const scoped_refptr<base::TaskRunner>& background_task_runner);
+      const scoped_refptr<base::TaskRunner>& background_task_runner,
+      std::unique_ptr<image_fetcher::ImageFetcher> image_fetcher);
   ~LargeIconService() override;
 
   // Requests the best large icon for the page at |page_url|.
@@ -49,6 +54,26 @@ class LargeIconService : public KeyedService {
     const favicon_base::LargeIconCallback& callback,
     base::CancelableTaskTracker* tracker);
 
+  // Fetches the best large icon for the page at |page_url| from a Google
+  // favicon server and stores the result in the FaviconService cache
+  // (implemented in HistoryService). The write will be a no-op if the local
+  // favicon cache contains an icon for |page_url|, so clients are encouraged to
+  // use GetLargeIconOrFallbackStyle() first.
+  //
+  // A minimum size |min_source_size_in_pixel| can be specified as constraint.
+  //
+  // The callback is triggered when the operation finishes, where |success|
+  // tells whether the fetch actually managed to cache a new icon in the
+  // FaviconService.
+  //
+  // WARNING: This function will share the |page_url| with a Google server. This
+  // Can be used only for urls that are not privacy sensitive or for users that
+  // sync their history with Google servers.
+  void GetLargeIconOrFallbackStyleFromGoogleServerSkippingLocalCache(
+      const GURL& page_url,
+      int min_source_size_in_pixel,
+      const base::Callback<void(bool success)>& callback);
+
  private:
   FaviconService* favicon_service_;
   scoped_refptr<base::TaskRunner> background_task_runner_;
@@ -58,6 +83,8 @@ class LargeIconService : public KeyedService {
   // request.
   std::vector<int> large_icon_types_;
 
+  std::unique_ptr<image_fetcher::ImageFetcher> image_fetcher_;
+
   DISALLOW_COPY_AND_ASSIGN(LargeIconService);
 };