NTPSnippets: Set MaxRetriesOn5xx only for interactive requests.

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 62236a8a375cab50981b1a7798b0ce55f963798c..8aa0580e0b3e85259f478744d7cf94a1e76b07d1 100644
--- a/components/ntp_snippets/remote/ntp_snippets_fetcher.cc
+++ b/components/ntp_snippets/remote/ntp_snippets_fetcher.cc
@@ -661,6 +661,13 @@ NTPSnippetsFetcher::RequestBuilder::SetUserClassifier(
   return *this;
 }
 
+std::unique_ptr<net::URLFetcher>
+NTPSnippetsFetcher::RequestBuilder::PreviewURLFetcherForTesting() const {
+  return BuildURLFetcher(/*request=*/nullptr,  // Can never be called anyways.

[tschumann, 2016/12/05 17:26:33]

this is a smell. If you really need something like this, then subclass the
builder, do this modification there and test it. But again, I'd much rather have
the test using the public interface and test the actual class.

[fhorschig, 2016/12/06 14:31:40]

Removed. As noted in your last comment, this was easy to do with the
TestURLFetcher.

+                         /*headers=*/"",       // Can be set later if needed.
+                         /*body=*/"");         // Can be set later if needed.
+}
+
 bool NTPSnippetsFetcher::RequestBuilder::IsSendingTopLanguagesEnabled() const {
   return IsBooleanParameterEnabled(kSendTopLanguagesName,
                                    /*default_value=*/false);
@@ -812,8 +819,14 @@ NTPSnippetsFetcher::RequestBuilder::BuildURLFetcher(
 
   // Fetchers are sometimes cancelled because a network change was detected.
   url_fetcher->SetAutomaticallyRetryOnNetworkChanges(3);
-  // Try to make fetching the files bit more robust even with poor connection.
-  url_fetcher->SetMaxRetriesOn5xx(3);
+  if (params_.interactive_request) {
+    // Try to make fetching the files bit more robust even with poor connection.
+    url_fetcher->SetMaxRetriesOn5xx(2);
+  } else {
+    // Don't retry immediately if a scheduled fetch fails.
+    // TODO(fhorschig): back off for 1h (+1h jitter) and then retry.
+    url_fetcher->SetMaxRetriesOn5xx(0);
+  }
   return url_fetcher;
 }