Move testing of Loading Predictor optimization guide to unit tests

This also re-enables the browser tests since the flakes were mostly tied
to the UMA histogram reporting.

Bug: 1060966,1060397
Change-Id: I67a1dfafa5d220e3a2165981e4bd4a6812174aa8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2134645
Commit-Queue: Sophie Chang <sophiechang@chromium.org>
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756093}

chrome/browser/predictors/loading_predictor_browsertest.cc

@@ -1541,6 +1541,14 @@ class LoadingPredictorBrowserTestWithOptimizationGuide
     }
   }
 
+  void SetUpOnMainThread() override {
+    // Wait until command line hints have been processed before proceeding with
+    // tests.
+    RetryForHistogramUntilCountReached(
+        histogram_tester_, "OptimizationGuide.UpdateComponentHints.Result", 1);
+    LoadingPredictorBrowserTest::SetUpOnMainThread();
+  }
+
   void SetUpCommandLine(base::CommandLine* command_line) override {
     // TODO(crbug/1035698): Make this simpler when Optimization Guide has better
     // test support.
@@ -1585,6 +1593,7 @@ class LoadingPredictorBrowserTestWithOptimizationGuide
   }
 
  private:
+  base::HistogramTester histogram_tester_;
   base::test::ScopedFeatureList feature_list_;
   base::test::ScopedFeatureList local_predictions_feature_list_;
 };
@@ -1600,9 +1609,9 @@ INSTANTIATE_TEST_SUITE_P(,
 #define DISABLE_ON_WIN_MAC_CHROMEOS(x) x
 #endif
 
-IN_PROC_BROWSER_TEST_P(
-    LoadingPredictorBrowserTestWithOptimizationGuide,
-    DISABLED_NavigationHasLocalPredictionNoOptimizationHint) {
+IN_PROC_BROWSER_TEST_P(LoadingPredictorBrowserTestWithOptimizationGuide,
+                       DISABLE_ON_WIN_MAC_CHROMEOS(
+                           NavigationHasLocalPredictionNoOptimizationHint)) {
   // Navigate the first time to fill the predictor's database and the HTTP
   // cache.
   GURL url = embedded_test_server()->GetURL(
@@ -1613,8 +1622,6 @@ IN_PROC_BROWSER_TEST_P(
   ui_test_utils::NavigateToURL(browser(), url);
   ResetNetworkState();
 
-  base::HistogramTester histogram_tester;
-
   auto observer = NavigateToURLAsync(url);
   EXPECT_TRUE(observer->WaitForRequestStart());
   for (auto* const host : kHtmlSubresourcesHosts) {
@@ -1641,20 +1648,12 @@ IN_PROC_BROWSER_TEST_P(
             connection_tracker()->GetAcceptedSocketCount());
   // No reads since all resources should be cached.
   EXPECT_EQ(0u, connection_tracker()->GetReadSocketCount());
-
-  if (IsLocalPredictionEnabled()) {
-    histogram_tester.ExpectTotalCount(
-        "LoadingPredictor.OptimizationHintsReceiveStatus", 0);
-  } else {
-    histogram_tester.ExpectTotalCount(
-        "LoadingPredictor.OptimizationHintsReceiveStatus", 1);
-  }
 }
 
-// TODO(crbug.com/1060966): Tests are flakey.
 IN_PROC_BROWSER_TEST_P(
     LoadingPredictorBrowserTestWithOptimizationGuide,
-    DISABLED_NavigationWithBothLocalPredictionAndOptimizationHint) {
+    DISABLE_ON_WIN_MAC_CHROMEOS(
+        NavigationWithBothLocalPredictionAndOptimizationHint)) {
   base::HistogramTester histogram_tester;
 
   GURL url = embedded_test_server()->GetURL(
@@ -1705,32 +1704,12 @@ IN_PROC_BROWSER_TEST_P(
     EXPECT_TRUE(preconnect_manager_observer()->HasOriginAttemptedToPreconnect(
         expected_origin));
   }
-
-  if (IsLocalPredictionEnabled()) {
-    histogram_tester.ExpectUniqueSample(
-        "LoadingPredictor.OptimizationHintsReceiveStatus",
-        OptimizationHintsReceiveStatus::kAfterNavigationFinish, 1);
-  } else {
-    // We expect one for the setup navigation and one for the navigation we care
-    // about.
-    histogram_tester.ExpectTotalCount(
-        "LoadingPredictor.OptimizationHintsReceiveStatus", 2);
-    // We expect the hints to arrive before navigation for the navigation we
-    // care about.
-    histogram_tester.ExpectBucketCount(
-        "LoadingPredictor.OptimizationHintsReceiveStatus",
-        OptimizationHintsReceiveStatus::kBeforeNavigationFinish, 1);
-    // We expect the decision to arrive at finish for the setup navigation.
-    histogram_tester.ExpectBucketCount(
-        "LoadingPredictor.OptimizationHintsReceiveStatus",
-        OptimizationHintsReceiveStatus::kAfterNavigationFinish, 1);
-  }
 }
 
-// crbug.com/1060966
 IN_PROC_BROWSER_TEST_P(
     LoadingPredictorBrowserTestWithOptimizationGuide,
-    DISABLED_NavigationWithNoLocalPredictionsButHasOptimizationHint) {
+    DISABLE_ON_WIN_MAC_CHROMEOS(
+        NavigationWithNoLocalPredictionsButHasOptimizationHint)) {
   {
     base::HistogramTester histogram_tester;
 
@@ -1798,30 +1777,13 @@ IN_PROC_BROWSER_TEST_P(
         "LoadingPredictor.PreconnectLearningPrecision.OptimizationGuide", 0, 1);
     histogram_tester.ExpectUniqueSample(
         "LoadingPredictor.PreconnectLearningCount.OptimizationGuide", 2, 1);
-
-    // We expect one for the final navigation and one for the navigation we care
-    // about.
-    histogram_tester.ExpectTotalCount(
-        "LoadingPredictor.OptimizationHintsReceiveStatus", 2);
-    // We expect the hints to arrive before navigation for the navigation we
-    // care about.
-    histogram_tester.ExpectBucketCount(
-        "LoadingPredictor.OptimizationHintsReceiveStatus",
-        OptimizationHintsReceiveStatus::kBeforeNavigationFinish, 1);
-    // We expect the decision to arrive at finish for the navigation we do not
-    // have hints for.
-    histogram_tester.ExpectBucketCount(
-        "LoadingPredictor.OptimizationHintsReceiveStatus",
-        OptimizationHintsReceiveStatus::kAfterNavigationFinish, 1);
   }
 }
 
-// TODO(crbug.com/1060966): Tests are flakey.
 IN_PROC_BROWSER_TEST_P(
     LoadingPredictorBrowserTestWithOptimizationGuide,
-    DISABLED_OptimizationGuidePredictionsNotAppliedForAlreadyCommittedNavigation) {
-  base::HistogramTester histogram_tester;
-
+    DISABLE_ON_WIN_MAC_CHROMEOS(
+        OptimizationGuidePredictionsNotAppliedForAlreadyCommittedNavigation)) {
   GURL url = embedded_test_server()->GetURL("hints.com", "/simple.html");
   url::Origin origin = url::Origin::Create(url);
   net::NetworkIsolationKey network_isolation_key(origin, origin);
@@ -1833,17 +1795,11 @@ IN_PROC_BROWSER_TEST_P(
       "subresource.com", network_isolation_key));
   EXPECT_FALSE(preconnect_manager_observer()->HasHostBeenLookedUp(
       "otheresource.com", network_isolation_key));
-
-  histogram_tester.ExpectUniqueSample(
-      "LoadingPredictor.OptimizationHintsReceiveStatus",
-      OptimizationHintsReceiveStatus::kAfterNavigationFinish, 1);
 }
 
 IN_PROC_BROWSER_TEST_P(LoadingPredictorBrowserTestWithOptimizationGuide,
                        DISABLE_ON_WIN_MAC_CHROMEOS(
                            OptimizationGuidePredictionsNotAppliedForRedirect)) {
-  base::HistogramTester histogram_tester;
-
   GURL destination_url =
       embedded_test_server()->GetURL("otherhost.com", "/cachetime");
   GURL redirecting_url = embedded_test_server()->GetURL(
@@ -1859,11 +1815,6 @@ IN_PROC_BROWSER_TEST_P(LoadingPredictorBrowserTestWithOptimizationGuide,
       "subresource.com", network_isolation_key));
   EXPECT_FALSE(preconnect_manager_observer()->HasHostBeenLookedUp(
       "otheresource.com", network_isolation_key));
-
-  // We cannot force when the hint comes back, so we make sure that we at least
-  // received something back from the optimization guide instead.
-  histogram_tester.ExpectTotalCount(
-      "LoadingPredictor.OptimizationHintsReceiveStatus", 1);
 }
 
 class LoadingPredictorBrowserTestWithNoLocalPredictions

chrome/browser/predictors/loading_predictor_tab_helper.cc

@@ -308,8 +308,12 @@ void LoadingPredictorTabHelper::OnOptimizationGuideDecision(
   if (decision != optimization_guide::OptimizationGuideDecision::kTrue)
     return;
 
-  if (!metadata.loading_predictor_metadata())
+  if (!metadata.loading_predictor_metadata()) {
+    // Metadata is not applicable, so just log an unknown decision.
+    last_optimization_guide_prediction_->decision =
+        optimization_guide::OptimizationGuideDecision::kUnknown;
     return;
+  }
 
   PreconnectPrediction prediction;
   url::Origin main_frame_origin =