Find Favicon in priority of icon_type.

chrome/browser/history/history_service.h

Index: chrome/browser/history/history_service.h
diff --git a/chrome/browser/history/history_service.h b/chrome/browser/history/history_service.h
index 6891f38e71498c86140cb025cf5bfcdd1afeb5a2..f1196bc901074ce4b5e52947af84f5e7d852c4d4 100644
--- a/chrome/browser/history/history_service.h
+++ b/chrome/browser/history/history_service.h
@@ -690,19 +690,32 @@ class HistoryService : public CancelableRequestProvider,
       const FaviconService::FaviconResultsCallback& callback,
       CancelableTaskTracker* tracker);
 
-  // Used by the FaviconService to get favicons mapped to |page_url| for
-  // |icon_types| which most closely match |desired_size_in_dip| and
-  // |desired_scale_factors|. If |desired_size_in_dip| is 0, the largest favicon
-  // bitmap for |icon_types| is returned. The returned FaviconBitmapResults will
+  // Used by the FaviconService to get favicons mapped to |params.page_url| for
+  // icon_types in |params.icon_types| which most closely match
+  // |params.desired_size_in_dip| and |desired_scale_factors|.
+  // If |desired_size_in_dip| is 0, the largest favicon bitmap for
+  // |params.icon_types| is returned. The returned FaviconBitmapResults will
   // have at most one result for each of |desired_scale_factors|. If a favicon
   // bitmap is determined to be the best candidate for multiple scale factors
-  // there will be less results. If |icon_types| has several types, results for
+  // there will be less results.
+  // |params.icon_types| is a list of icon_type composition and defines the
+  // prefered icon types in priority.
+  // If it has only one element, and this element has several types, results for
   // only a single type will be returned in the priority of
   // TOUCH_PRECOMPOSED_ICON, TOUCH_ICON, and FAVICON.
+  // if it has more than one element, there is only one icon returned by below
+  // rule:
+  // Among all icons found by |params.desired_size_in_dip| and
+  // |desired_scal_factors|, the largest icon of first types given by
+  // |params.icon_types| is returned, if its size is larger than
+  // |params.threshold_for_next_icon_types|; otherwise, find the largest one
+  // in next icon types in |params.icon_types| and so on.
+  // If none icon is larger than |threshold_for_next_icon_types|, the largest
+  // one among all found icon is returned.
+  // This feature is especially useful when some types of icon is perfered as
+  // long as its size is larger than a specific value.
   CancelableTaskTracker::TaskId GetFaviconsForURL(
-      const GURL& page_url,
-      int icon_types,
-      int desired_size_in_dip,
+      const FaviconService::FaviconForURLParams& params,
       const std::vector<ui::ScaleFactor>& desired_scale_factors,
       const FaviconService::FaviconResultsCallback& callback,
       CancelableTaskTracker* tracker);