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..23d5cf8f1dd3dcd5f9ac1592aa2a8845900988e7 100644
--- a/components/favicon/core/large_icon_service.h
+++ b/components/favicon/core/large_icon_service.h
@@ -5,6 +5,7 @@
 #ifndef COMPONENTS_FAVICON_CORE_LARGE_ICON_SERVICE_H_
 #define COMPONENTS_FAVICON_CORE_LARGE_ICON_SERVICE_H_
 
+#include <string>
 #include <vector>
 
 #include "base/macros.h"
@@ -18,6 +19,10 @@ namespace base {
 class TaskRunner;
 }
 
+namespace image_fetcher {
+class ImageFetcher;
+}
+
 namespace favicon {
 
 class FaviconService;
@@ -28,7 +33,8 @@ 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|.
@@ -49,14 +55,34 @@ 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. Similarly to |GetLargeIconOrFallbackStyle|.
+  // Case 1. An icon is fetched whose size is >= |min_source_size_in_pixel|:
+  // - If |desired_size_in_pixel| == 0: returns icon as is.
+  // - Else: returns the icon resized to |desired_size_in_pixel|.
+  // Case 2. An icon is fetched whose size is < |min_source_size_in_pixel|:
+  // - Extracts dominant color of smaller image, returns a fallback icon style
+  //   that has a matching background.
+  // Case 3. No icon exists.
+  // - Returns the default fallback icon style.
+  // For cases 2 and 3, this function returns the style of the fallback icon
+  // instead of rendering an icon so clients can render the icon themselves.
+  // 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.
+  base::CancelableTaskTracker::TaskId
+  GetLargeIconOrFallbackStyleFromGoogleServerSkippingLocalCache(
+      const GURL& page_url,
+      int min_source_size_in_pixel,
+      int desired_size_in_pixel,
+      const favicon_base::LargeIconCallback& callback,
+      base::CancelableTaskTracker* tracker);
+
  private:
   FaviconService* favicon_service_;
   scoped_refptr<base::TaskRunner> background_task_runner_;
 
-  // A pre-populated list of icon types to consider when looking for large
-  // icons. This is an optimization over populating an icon type vector on each
-  // request.
-  std::vector<int> large_icon_types_;
+  std::unique_ptr<image_fetcher::ImageFetcher> image_fetcher_;
 
   DISALLOW_COPY_AND_ASSIGN(LargeIconService);
 };