Ignore duplicate FaviconHandler::OnUpdateFaviconURL() calls

components/favicon/core/favicon_handler.h

 // Copyright (c) 2012 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 COMPONENTS_FAVICON_CORE_FAVICON_HANDLER_H_
 #define COMPONENTS_FAVICON_CORE_FAVICON_HANDLER_H_
 
 #include <map>
 #include <vector>
 
@@ skipping 213 matching lines @@
   // Notifies |driver_| favicon available. See
   // FaviconDriver::NotifyFaviconAvailable() for |is_active_favicon| in detail.
   void NotifyFaviconAvailable(
       const std::vector<favicon_base::FaviconRawBitmapResult>&
           favicon_bitmap_results);
   void NotifyFaviconAvailable(const GURL& icon_url,
                               const gfx::Image& image);
 
   // Return the current candidate if any.
   favicon::FaviconURL* current_candidate() {
-    return (!image_urls_.empty()) ? &image_urls_.front() : NULL;
+    return current_candidate_index_ < image_urls_.size()
+               ? &image_urls_[current_candidate_index_]
+               : nullptr;
   }
 
   // Returns the preferred size of the image. 0 means no preference (any size
   // will do).
   int preferred_icon_size() const {
     if (download_largest_icon_)
       return 0;
     return handler_type_ == FAVICON ? gfx::kFaviconSize : 0;
   }
 
-  // Sorts the entries in |image_urls_| by icon size in descending order.
-  // Additionally removes any entries whose sizes are all greater than the max
-  // allowed size.
-  void SortAndPruneImageUrls();
+  // Sorts the entries in |image_urls| by icon size in descending order.
+  // Discards all but the largest size for each FaviconURL.
+  void SortAndPruneImageUrls(std::vector<FaviconURL>* image_urls);
 
   // Used for FaviconService requests.
   base::CancelableTaskTracker cancelable_task_tracker_;
 
   // URL of the page we're requesting the favicon for.
   GURL url_;
 
   // Whether we got data back for the initial request to the FaviconService.
   bool got_favicon_from_history_;
 
@@ skipping 22 matching lines @@
   // The FaviconRawBitmapResults from history.
   std::vector<favicon_base::FaviconRawBitmapResult> history_results_;
 
   // The FaviconService which implements favicon operations. May be null during
   // testing.
   FaviconService* service_;
 
   // This handler's driver, owns this object.
   FaviconDriver* driver_;
 
+  // The index of the favicon URL in |image_urls_| which is currently being
+  // requested from history or downloaded.
+  size_t current_candidate_index_;
+
   // Best image we've seen so far.  As images are downloaded from the page they
   // are stored here. When there is an exact match, or no more images are
   // available the favicon service and the current page are updated (assuming
   // the image is for a favicon).
   FaviconCandidate best_favicon_candidate_;
 
   DISALLOW_COPY_AND_ASSIGN(FaviconHandler);
 };
 
 }  // namespace favicon
 
 #endif  // COMPONENTS_FAVICON_CORE_FAVICON_HANDLER_H_