[EoC] Check confidence on cached results

Bug: 849456
Change-Id: I296348c5fd7e4bb99c1c88694d05f80245d7d8fa
Reviewed-on: https://chromium-review.googlesource.com/1087685Reviewed-by: Filip Gorski <fgorski@chromium.org>
Commit-Queue: Patrick Noland <pnoland@chromium.org>
Cr-Commit-Position: refs/heads/master@{#564676}

components/ntp_snippets/contextual/contextual_content_suggestions_service.cc

@@ -64,6 +64,8 @@ void ContextualContentSuggestionsService::FetchContextualSuggestionClusters(
         url, std::move(callback), metrics_callback);
     contextual_suggestions_fetcher_->FetchContextualSuggestionsClusters(
         url, std::move(internal_callback), metrics_callback);
+  } else if (result.peek_conditions.confidence < kMinimumConfidence) {
+    BelowConfidenceThresholdFetchDone(std::move(callback), metrics_callback);
   } else {
     std::move(callback).Run(result);
   }
@@ -90,9 +92,7 @@ void ContextualContentSuggestionsService::FetchDone(
   }
 
   if (result.peek_conditions.confidence < kMinimumConfidence) {
-    metrics_callback.Run(contextual_suggestions::FETCH_BELOW_THRESHOLD);
-    std::move(callback).Run(
-        ContextualSuggestionsResult("", {}, PeekConditions()));
+    BelowConfidenceThresholdFetchDone(std::move(callback), metrics_callback);
     return;
   }
 
@@ -107,4 +107,12 @@ ContextualContentSuggestionsService::CreateProxy() {
       this, reporter_provider_->CreateReporter());
 }
 
+void ContextualContentSuggestionsService::BelowConfidenceThresholdFetchDone(
+    FetchClustersCallback callback,
+    ReportFetchMetricsCallback metrics_callback) {
+  metrics_callback.Run(contextual_suggestions::FETCH_BELOW_THRESHOLD);
+  std::move(callback).Run(
+      ContextualSuggestionsResult("", {}, PeekConditions()));
+}
+
 }  // namespace contextual_suggestions

components/ntp_snippets/contextual/contextual_content_suggestions_service.h

@@ -68,6 +68,9 @@ class ContextualContentSuggestionsService : public KeyedService {
   std::unique_ptr<ContextualContentSuggestionsServiceProxy> CreateProxy();
 
  private:
+  void BelowConfidenceThresholdFetchDone(
+      FetchClustersCallback callback,
+      ReportFetchMetricsCallback metrics_callback);
   // Cache for images of contextual suggestions, needed by CachedImageFetcher.
   std::unique_ptr<ntp_snippets::RemoteSuggestionsDatabase>
       contextual_suggestions_database_;

components/ntp_snippets/contextual/contextual_content_suggestions_service_unittest.cc

@@ -279,4 +279,37 @@ TEST_F(ContextualContentSuggestionsServiceTest, ShouldEvictOldCachedResults) {
   EXPECT_EQ(mock_callback.response_clusters.size(), 0u);
 }
 
+TEST_F(ContextualContentSuggestionsServiceTest,
+       ShouldNotReturnCachedLowConfidenceResults) {
+  MockClustersCallback mock_callback;
+  MockClustersCallback mock_callback2;
+  std::vector<Cluster> clusters;
+  GURL context_url("http://www.from.url");
+
+  clusters.emplace_back(ClusterBuilder("Title")
+                            .AddSuggestion(SuggestionBuilder(context_url)
+                                               .Title("Title1")
+                                               .PublisherName("from.url")
+                                               .Snippet("Summary")
+                                               .ImageId("abc")
+                                               .Build())
+                            .Build());
+  PeekConditions peek_conditions;
+  peek_conditions.confidence = 0;
+  fetcher()->SetFakeResponse(clusters, peek_conditions);
+  source()->FetchContextualSuggestionClusters(
+      context_url, mock_callback.ToOnceCallback(), base::DoNothing());
+  base::RunLoop().RunUntilIdle();
+
+  EXPECT_TRUE(mock_callback.has_run);
+  ExpectResponsesMatch(mock_callback, ContextualSuggestionsResult());
+
+  // The cached result we get back should be empty, since its confidence is
+  // below the threshold.
+  source()->FetchContextualSuggestionClusters(
+      context_url, mock_callback2.ToOnceCallback(), base::DoNothing());
+  EXPECT_TRUE(mock_callback2.has_run);
+  ExpectResponsesMatch(mock_callback2, ContextualSuggestionsResult());
+}
+
 }  // namespace contextual_suggestions