[NTP Snippets] Pass "no suggestions" message from the backend to the UI

components/ntp_snippets/category_info.h

Index: components/ntp_snippets/category_info.h
diff --git a/components/ntp_snippets/category_info.h b/components/ntp_snippets/category_info.h
index 1a659ed232da0099d91745ebbbab24c13a25490a..78cd53ce682f5783d79121a174076a698825d31c 100644
--- a/components/ntp_snippets/category_info.h
+++ b/components/ntp_snippets/category_info.h
@@ -26,7 +26,8 @@ class CategoryInfo {
   CategoryInfo(const base::string16& title,
                ContentSuggestionsCardLayout card_layout,
                bool has_more_button,
-               bool show_if_empty);
+               bool show_if_empty,
+               const base::string16& no_suggestions_message);
   CategoryInfo(CategoryInfo&&) = default;
   CategoryInfo& operator=(CategoryInfo&&) = default;
 
@@ -46,11 +47,19 @@ class CategoryInfo {
   // Whether this category should be shown if it offers no suggestions.
   bool show_if_empty() const { return show_if_empty_; }
 
+  // The message to show if there are no suggestions in this category. Note that
+  // this matters even if |show_if_empty()| is false: The message still shows
+  // up when the user dismisses all suggestions in the category.
+  const base::string16& no_suggestions_message() const {
+    return no_suggestions_message_;
+  }
+
  private:
   base::string16 title_;
   ContentSuggestionsCardLayout card_layout_;
   bool has_more_button_;
   bool show_if_empty_;
+  base::string16 no_suggestions_message_;
 
   DISALLOW_COPY_AND_ASSIGN(CategoryInfo);
 };