[NTP Snippets] Add unit tests for NTPSnippetsFetcher

components/ntp_snippets/ntp_snippets_fetcher.cc

Index: components/ntp_snippets/ntp_snippets_fetcher.cc
diff --git a/components/ntp_snippets/ntp_snippets_fetcher.cc b/components/ntp_snippets/ntp_snippets_fetcher.cc
index 2cb82135958e12b116cb883a50fef15634f8b8c3..89d26f7810f129fd1eae9449bbcd0405a564b372 100644
--- a/components/ntp_snippets/ntp_snippets_fetcher.cc
+++ b/components/ntp_snippets/ntp_snippets_fetcher.cc
@@ -86,13 +86,13 @@ NTPSnippetsFetcher::AddCallback(const SnippetsAvailableCallback& callback) {
 
 void NTPSnippetsFetcher::FetchSnippets(const std::set<std::string>& hosts,
                                        int count) {
-  // TODO(treib): What to do if there's already a pending request?
   const std::string& key = is_stable_channel_
                                ? google_apis::GetAPIKey()
                                : google_apis::GetNonStableAPIKey();
   std::string url =
       base::StringPrintf(kContentSnippetsServerFormat, key.c_str());
   url_fetcher_ = URLFetcher::Create(GURL(url), URLFetcher::POST, this);
+  CHECK(url_fetcher_ != nullptr);

[Marc Treib, 2016/05/03 11:33:42]

DCHECK please (DCHECKS are enabled on all the bots, so it'll still get
exercised).
Also the "!= nullptr" isn't required, and is usually omitted in Chromium.

[mastiz, 2016/05/03 11:48:57]

Done. Removed, as discussed offline.

   url_fetcher_->SetRequestContext(url_request_context_getter_.get());
   url_fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SEND_COOKIES |
                              net::LOAD_DO_NOT_SAVE_COOKIES);