Add a message to empty ContentSuggestions sections

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/memory/ptr_util.h"
 #include "base/optional.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 79 matching lines @@
 // Returns a SectionInformation for a |category|, filled with the
 // |categoryInfo|.
 ContentSuggestionsSectionInformation* SectionInformationFromCategoryInfo(
     const base::Optional<ntp_snippets::CategoryInfo>& categoryInfo,
     const ntp_snippets::Category& category) {
   ContentSuggestionsSectionInformation* sectionInfo =
       [[ContentSuggestionsSectionInformation alloc]
           initWithSectionID:SectionIDForCategory(category)];
   if (categoryInfo) {
     sectionInfo.layout = SectionLayoutForLayout(categoryInfo->card_layout());
-    if (categoryInfo->show_if_empty()) {
-      // TODO(crbug.com/686728): Creates an item to display information when the
-      // section is empty.
-    }
+    sectionInfo.showIfEmpty = categoryInfo->show_if_empty();
+    sectionInfo.emptyText =
+        base::SysUTF16ToNSString(categoryInfo->no_suggestions_message());
     if (categoryInfo->additional_action() !=
         ntp_snippets::ContentSuggestionsAdditionalAction::NONE) {
       sectionInfo.footerTitle =
           l10n_util::GetNSString(IDS_IOS_CONTENT_SUGGESTIONS_FOOTER_TITLE);
     }
     sectionInfo.title = base::SysUTF16ToNSString(categoryInfo->title());
   }
   return sectionInfo;
 }
 
@@ skipping 195 matching lines @@
           suggestionIdentifier.IDInSection),
       base::BindBlockArc(callback));
 }
 
 #pragma mark - Private
 
 - (void)addSuggestions:
             (const std::vector<ntp_snippets::ContentSuggestion>&)suggestions
           fromCategory:(ntp_snippets::Category&)category
                toArray:(NSMutableArray<ContentSuggestion*>*)contentArray {
-  if (self.contentService->GetCategoryStatus(category) !=
-      ntp_snippets::CategoryStatus::AVAILABLE) {
+  if (!ntp_snippets::IsCategoryStatusAvailable(
+          self.contentService->GetCategoryStatus(category))) {
     return;
   }
 
   ContentSuggestionsCategoryWrapper* categoryWrapper =
       [ContentSuggestionsCategoryWrapper wrapperWithCategory:category];
   if (!self.sectionInformationByCategory[categoryWrapper]) {
     [self addSectionInformationForCategory:category];
   }
 
   for (auto& contentSuggestion : suggestions) {
     ContentSuggestion* suggestion = ConvertContentSuggestion(contentSuggestion);
 
     suggestion.type = TypeForCategory(category);
 
     suggestion.suggestionIdentifier.sectionInfo =
         self.sectionInformationByCategory[categoryWrapper];
 
     [contentArray addObject:suggestion];
   }
+
+  if (suggestions.size() == 0) {
+    ContentSuggestion* suggestion = [[ContentSuggestion alloc] init];
+    suggestion.type = ContentSuggestionTypeEmpty;
+    suggestion.suggestionIdentifier =
+        [[ContentSuggestionIdentifier alloc] init];
+    suggestion.suggestionIdentifier.sectionInfo =
+        self.sectionInformationByCategory[categoryWrapper];
+
+    [contentArray addObject:suggestion];
+  }
 }
 
 - (void)addSectionInformationForCategory:(ntp_snippets::Category)category {
   base::Optional<ntp_snippets::CategoryInfo> categoryInfo =
       self.contentService->GetCategoryInfo(category);
 
   ContentSuggestionsSectionInformation* sectionInfo =
       SectionInformationFromCategoryInfo(categoryInfo, category);
 
   self.sectionInformationByCategory[[ContentSuggestionsCategoryWrapper
@@ skipping 17 matching lines @@
         [NSMutableArray array];
     ntp_snippets::Category category = suggestions[0].id().category();
     [self addSuggestions:suggestions
             fromCategory:category
                  toArray:contentSuggestions];
     callback(contentSuggestions);
   }
 }
 
 @end