Adds a Fetch() method to the ContentSuggestionService which asks any provider to provide more conte…

chrome/browser/ntp_snippets/download_suggestions_provider.cc

Index: chrome/browser/ntp_snippets/download_suggestions_provider.cc
diff --git a/chrome/browser/ntp_snippets/download_suggestions_provider.cc b/chrome/browser/ntp_snippets/download_suggestions_provider.cc
index 23e14af664846b03c6d8c4fe3180b693fc2f5f9a..a5c07d1848dadfbb59230f185a8e23468b477a6b 100644
--- a/chrome/browser/ntp_snippets/download_suggestions_provider.cc
+++ b/chrome/browser/ntp_snippets/download_suggestions_provider.cc
@@ -5,6 +5,7 @@
 #include "chrome/browser/ntp_snippets/download_suggestions_provider.h"
 
 #include <algorithm>
+#include <utility>
 
 #include "base/bind.h"
 #include "base/feature_list.h"
@@ -162,6 +163,16 @@ void DownloadSuggestionsProvider::FetchSuggestionImage(
       FROM_HERE, base::Bind(callback, gfx::Image()));
 }
 
+void DownloadSuggestionsProvider::Fetch(
+    const ntp_snippets::Category& category,
+    const std::set<std::string>& known_suggestion_ids,
+    FetchingCallback callback) {
+  NOTREACHED();
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE,
+      base::Bind(callback, base::Passed(std::vector<ContentSuggestion>())));
+}
+
 void DownloadSuggestionsProvider::ClearHistory(
     base::Time begin,
     base::Time end,