Reload the Most Visited section when it changes

ios/chrome/browser/content_suggestions/content_suggestions_mediator.mm

 // Copyright 2017 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.
 
 #import "ios/chrome/browser/content_suggestions/content_suggestions_mediator.h"
 
 #include "base/mac/bind_objc_block.h"
 #include "base/mac/foundation_util.h"
 #include "base/memory/ptr_util.h"
 #include "base/optional.h"
@@ skipping 35 matching lines @@
 
 @interface ContentSuggestionsMediator ()<ContentSuggestionsImageFetcher,
                                          ContentSuggestionsServiceObserver,
                                          MostVisitedSitesObserving> {
   // Bridge for this class to become an observer of a ContentSuggestionsService.
   std::unique_ptr<ContentSuggestionsServiceBridge> _suggestionBridge;
   std::unique_ptr<ntp_tiles::MostVisitedSites> _mostVisitedSites;
   std::unique_ptr<ntp_tiles::MostVisitedSitesObserverBridge> _mostVisitedBridge;
 }
 
-// Most visited items from the MostVisitedSites service (copied upon receiving
-// the callback).
+// Most visited items from the MostVisitedSites service currently displayed.
 @property(nonatomic, strong)
     NSMutableArray<ContentSuggestionsMostVisitedItem*>* mostVisitedItems;
+// Most visited items from the MostVisitedSites service (copied upon receiving
+// the callback). Those items are up to date with the model.
+@property(nonatomic, strong)
+    NSMutableArray<ContentSuggestionsMostVisitedItem*>* freshMostVisitedItems;
 // Section Info for the Most Visited section.
 @property(nonatomic, strong)
     ContentSuggestionsSectionInformation* mostVisitedSectionInfo;
 // Whether the page impression has been recorded.
 @property(nonatomic, assign) BOOL recordedPageImpression;
 // The ContentSuggestionsService, serving suggestions.
 @property(nonatomic, assign)
     ntp_snippets::ContentSuggestionsService* contentService;
 // Map the section information created to the relevant category.
 @property(nonatomic, strong, nonnull)
     NSMutableDictionary<ContentSuggestionsCategoryWrapper*,
                         ContentSuggestionsSectionInformation*>*
         sectionInformationByCategory;
 // FaviconAttributesProvider to fetch the favicon for the suggestions.
 @property(nonatomic, nullable, strong)
     FaviconAttributesProvider* attributesProvider;
 
 @end
 
 @implementation ContentSuggestionsMediator
 
 @synthesize mostVisitedItems = _mostVisitedItems;
+@synthesize freshMostVisitedItems = _freshMostVisitedItems;
 @synthesize mostVisitedSectionInfo = _mostVisitedSectionInfo;
 @synthesize recordedPageImpression = _recordedPageImpression;
 @synthesize contentService = _contentService;
 @synthesize dataSink = _dataSink;
 @synthesize sectionInformationByCategory = _sectionInformationByCategory;
 @synthesize attributesProvider = _attributesProvider;
 @synthesize commandHandler = _commandHandler;
 
 #pragma mark - Public
 
@@ skipping 28 matching lines @@
       [self categoryWrapperForSectionInfo:suggestionIdentifier.sectionInfo];
   ntp_snippets::ContentSuggestion::ID suggestion_id =
       ntp_snippets::ContentSuggestion::ID([categoryWrapper category],
                                           suggestionIdentifier.IDInSection);
 
   self.contentService->DismissSuggestion(suggestion_id);
 }
 
 - (void)blacklistMostVisitedURL:(GURL)URL {
   _mostVisitedSites->AddOrRemoveBlacklistedUrl(URL, true);
+  [self useFreshMostVisited];
 }
 
 - (void)whitelistMostVisitedURL:(GURL)URL {
   _mostVisitedSites->AddOrRemoveBlacklistedUrl(URL, false);
+  [self useFreshMostVisited];
 }
 
 #pragma mark - ContentSuggestionsDataSource
 
 - (NSArray<ContentSuggestionsSectionInformation*>*)sectionsInfo {
   NSMutableArray<ContentSuggestionsSectionInformation*>* sectionsInfo =
       [NSMutableArray array];
 
   if (self.mostVisitedItems.count > 0) {
     [sectionsInfo addObject:self.mostVisitedSectionInfo];
@@ skipping 218 matching lines @@
         }
 
         callback([image.ToUIImage() copy]);
       }));
 }
 
 #pragma mark - MostVisitedSitesObserving
 
 - (void)onMostVisitedURLsAvailable:
     (const ntp_tiles::NTPTilesVector&)mostVisited {
-  self.mostVisitedItems = [NSMutableArray array];
+  self.freshMostVisitedItems = [NSMutableArray array];
   for (const ntp_tiles::NTPTile& tile : mostVisited) {
-    [self.mostVisitedItems
+    [self.freshMostVisitedItems
         addObject:ConvertNTPTile(tile, self.mostVisitedSectionInfo)];
   }
 
-  [self.dataSink reloadSection:self.mostVisitedSectionInfo];
+  if ([self.mostVisitedItems count] > 0) {
+    // If some content is already displayed to the user, do not update without a
+    // user action.
+    return;
+  }
+
+  [self useFreshMostVisited];
 
   if (mostVisited.size() && !self.recordedPageImpression) {
     self.recordedPageImpression = YES;
     RecordPageImpression(mostVisited);
   }
 }
 
 - (void)onIconMadeAvailable:(const GURL&)siteURL {
   for (ContentSuggestionsMostVisitedItem* item in self.mostVisitedItems) {
     if (item.URL == siteURL) {
@@ skipping 68 matching lines @@
   callback(contentSuggestions);
 }
 
 // Returns whether the |sectionInfo| is associated with a category from the
 // content suggestions service.
 - (BOOL)isRelatedToContentSuggestionsService:
     (ContentSuggestionsSectionInformation*)sectionInfo {
   return sectionInfo != self.mostVisitedSectionInfo;
 }
 
+// Replaces the Most Visited items currently displayed by the most recent ones.
+- (void)useFreshMostVisited {
+  self.mostVisitedItems = self.freshMostVisitedItems;
+  [self.dataSink reloadSection:self.mostVisitedSectionInfo];
+}
+
 @end