NTP Snippets: Added error codes for out of quota events

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 c0018e7d816ad650ff06f25bdf664b5b64034e2e..22894d5442b680de6a46ecaa84be9dfd9513fa8d 100644
--- a/components/ntp_snippets/ntp_snippets_fetcher.cc
+++ b/components/ntp_snippets/ntp_snippets_fetcher.cc
@@ -86,6 +86,10 @@ std::string FetchResultToString(NTPSnippetsFetcher::FetchResult result) {
       return "Invalid / empty list.";
     case NTPSnippetsFetcher::FetchResult::OAUTH_TOKEN_ERROR:
       return "Error in obtaining an OAuth2 access token.";
+    case NTPSnippetsFetcher::FetchResult::INTERACTIVE_QUOTA_ERROR:
+      return "Out of interactive quota.";
+    case NTPSnippetsFetcher::FetchResult::NON_INTERACTIVE_QUOTA_ERROR:
+      return "Out of non-interactive quota.";
     case NTPSnippetsFetcher::FetchResult::RESULT_MAX:
       break;
   }
@@ -93,6 +97,18 @@ std::string FetchResultToString(NTPSnippetsFetcher::FetchResult result) {
   return "Unknown error";
 }
 
+bool isFetchPreconditionFailed(NTPSnippetsFetcher::FetchResult result) {

[Marc Treib, 2016/08/25 14:19:05]

nit: IsFetchPreconditionFailed (start with a capital letter)

+  switch (result) {
+    case NTPSnippetsFetcher::FetchResult::EMPTY_HOSTS:
+    case NTPSnippetsFetcher::FetchResult::OAUTH_TOKEN_ERROR:
+    case NTPSnippetsFetcher::FetchResult::INTERACTIVE_QUOTA_ERROR:
+    case NTPSnippetsFetcher::FetchResult::NON_INTERACTIVE_QUOTA_ERROR:
+      return true;
+    default:

[Marc Treib, 2016/08/25 14:19:05]

Instead of a default, I'd prefer to list the values explicitly. Then, when
someone adds a new value but doesn't list it here, they'll get a compile error.

+      return false;
+  }
+}
+
 std::string GetFetchEndpoint() {
   std::string endpoint = variations::GetVariationParamValue(
       ntp_snippets::kStudyName, kContentSuggestionsBackend);
@@ -218,8 +234,15 @@ void NTPSnippetsFetcher::FetchSnippetsFromHosts(
     const std::string& language_code,
     int count,
     bool interactive_request) {
-  if (!request_throttler_.DemandQuotaForRequest(interactive_request))
+  if (!request_throttler_.DemandQuotaForRequest(interactive_request)) {
+    FetchFinished(
+        OptionalSnippets(),
+        interactive_request ?
+          FetchResult::INTERACTIVE_QUOTA_ERROR :

[Marc Treib, 2016/08/25 14:19:05]

nit: wrong indentation I think? (You could try "git cl format")

+          FetchResult::NON_INTERACTIVE_QUOTA_ERROR,
+          /*extra_message=*/std::string());
     return;
+  }
 
   hosts_ = hosts;
   fetch_start_time_ = tick_clock_->NowTicks();
@@ -585,10 +608,9 @@ void NTPSnippetsFetcher::FetchFinished(OptionalSnippets snippets,
   DCHECK(result == FetchResult::SUCCESS || !snippets);
   last_status_ = FetchResultToString(result) + extra_message;
 
-  // If the result is EMPTY_HOSTS or OAUTH_TOKEN_ERROR, we didn't actually send
-  // a network request, so don't record FetchTime in those cases.
-  if (result != FetchResult::EMPTY_HOSTS &&
-      result != FetchResult::OAUTH_TOKEN_ERROR) {
+  // Don't record FetchTimes if the result indicates that a precondition
+  // failed and we never actually sent a network request
+  if (!isFetchPreconditionFailed(result)) {
     UMA_HISTOGRAM_TIMES("NewTabPage.Snippets.FetchTime",
                         tick_clock_->NowTicks() - fetch_start_time_);
   }