FetchMore functionality backend

components/ntp_snippets/remote/ntp_snippets_fetcher.cc

Index: components/ntp_snippets/remote/ntp_snippets_fetcher.cc
diff --git a/components/ntp_snippets/remote/ntp_snippets_fetcher.cc b/components/ntp_snippets/remote/ntp_snippets_fetcher.cc
index b40fd95633023caf30ae67a9d24121b769fad285..07866f7f939a067a36dab181c3012bd5b9a2c24e 100644
--- a/components/ntp_snippets/remote/ntp_snippets_fetcher.cc
+++ b/components/ntp_snippets/remote/ntp_snippets_fetcher.cc
@@ -316,11 +316,6 @@ NTPSnippetsFetcher::~NTPSnippetsFetcher() {
     token_service_->RemoveObserver(this);
 }
 
-void NTPSnippetsFetcher::SetCallback(
-    const SnippetsAvailableCallback& callback) {
-  snippets_available_callback_ = callback;
-}
-
 void NTPSnippetsFetcher::FetchSnippets(const Params& params) {
   if (!DemandQuotaForRequest(params.interactive_request)) {
     FetchFinished(OptionalFetchedCategories(),
@@ -738,6 +733,27 @@ void NTPSnippetsFetcher::OnJsonError(const std::string& error) {
       /*extra_message=*/base::StringPrintf(" (error %s)", error.c_str()));
 }
 
+void NTPSnippetsFetcher::FilterCategories(OptionalFetchedCategories* fetched)
+    const {
+  if (!fetched->has_value())
+    return;
+  if (!params_.exclusive_category.has_value())
+    return;
+  FetchedCategoriesVector* categories = &fetched->value();
+  Category exclusive = params_.exclusive_category.value();
+  auto category_it =
+      std::find_if(categories->begin(), categories->end(),
+                   [exclusive](const FetchedCategory& c) -> bool {
+                     return c.category == exclusive;
+                   });
+  if (category_it == categories->end()) {
+    categories->clear();
+    return;
+  }
+  categories->erase(categories->begin(), category_it);
+  categories->erase(category_it + 1, categories->end());
+}
+
 void NTPSnippetsFetcher::FetchFinished(
     OptionalFetchedCategories fetched_categories,
     FetchResult result,
@@ -745,6 +761,11 @@ void NTPSnippetsFetcher::FetchFinished(
   DCHECK(result == FetchResult::SUCCESS || !fetched_categories);
   last_status_ = FetchResultToString(result) + extra_message;
 
+  // TODO(fhorschig): Filter unwanted categories by sending the exclusive
+  // category to the backend. As soon as backends support this, there is no
+  // reason to overfetch and filter here.
+  FilterCategories(&fetched_categories);
+
   // Don't record FetchTimes if the result indicates that a precondition
   // failed and we never actually sent a network request
   if (!IsFetchPreconditionFailed(result)) {
@@ -756,8 +777,10 @@ void NTPSnippetsFetcher::FetchFinished(
                             static_cast<int>(FetchResult::RESULT_MAX));
 
   DVLOG(1) << "Fetch finished: " << last_status_;
-  if (!snippets_available_callback_.is_null())
-    snippets_available_callback_.Run(std::move(fetched_categories));
+  if (!params_.snippets_available_callback.is_null()) {
+    std::move(params_.snippets_available_callback).Run(

[vitaliii, 2016/11/01 23:29:57]

Why do you need this external |std::move|?

[fhorschig, 2016/11/02 05:05:27]

It's a "OnceCallback" that is consumed upon call:
https://chromium.googlesource.com/chromium/src/+/master/docs/callback.md

+        std::move(fetched_categories));
+  }
 }
 
 bool NTPSnippetsFetcher::DemandQuotaForRequest(bool interactive_request) {