NavigationPredictor: Disable on incognito profiles

In incognito profiles, do not predict the next navigation, either at
the time of load, or at the time of element click.

Bug: 899406
Change-Id: Iccddf772ed8fc5de63233e427e7eab35d8a3f20c
TBR: ryansturm@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/1330702Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607066}

chrome/browser/navigation_predictor/navigation_predictor.cc

@@ -152,6 +152,10 @@ TemplateURLService* NavigationPredictor::GetTemplateURLService() const {
 void NavigationPredictor::ReportAnchorElementMetricsOnClick(
     blink::mojom::AnchorElementMetricsPtr metrics) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
+
+  if (browser_context_->IsOffTheRecord())
+    return;
+
   if (!IsValidMetricFromRenderer(*metrics)) {
     mojo::ReportBadMessage("Bad anchor element metrics: onClick.");
     return;
@@ -343,6 +347,9 @@ void NavigationPredictor::ReportAnchorElementMetricsOnLoad(
   // Each document should only report metrics once when page is loaded.
   DCHECK(navigation_scores_map_.empty());
 
+  if (browser_context_->IsOffTheRecord())
+    return;
+
   if (metrics.empty()) {
     mojo::ReportBadMessage("Bad anchor element metrics: empty.");
     return;
@@ -460,6 +467,8 @@ double NavigationPredictor::CalculateAnchorNavigationScore(
     double target_engagement_score,
     int area_rank,
     int number_of_anchors) const {
+  DCHECK(!browser_context_->IsOffTheRecord());
+
   if (sum_scales_ == 0)
     return 0.0;
 
@@ -524,6 +533,8 @@ double NavigationPredictor::CalculateAnchorNavigationScore(
 void NavigationPredictor::MaybeTakeActionOnLoad(
     const std::vector<std::unique_ptr<NavigationScore>>&
         sorted_navigation_scores) const {
+  DCHECK(!browser_context_->IsOffTheRecord());
+
   // TODO(chelu): https://crbug.com/850624/. Given the calculated navigation
   // scores, this function decides which action to take, or decides not to do
   // anything. Example actions including preresolve, preload, prerendering, etc.
@@ -537,6 +548,8 @@ void NavigationPredictor::MaybeTakeActionOnLoad(
 
 void NavigationPredictor::RecordMetricsOnLoad(
     const blink::mojom::AnchorElementMetrics& metric) const {
+  DCHECK(!browser_context_->IsOffTheRecord());
+
   UMA_HISTOGRAM_PERCENTAGE("AnchorElementMetrics.Visible.RatioArea",
                            static_cast<int>(metric.ratio_area * 100));
 

chrome/browser/navigation_predictor/navigation_predictor_browsertest.cc

@@ -112,6 +112,21 @@ IN_PROC_BROWSER_TEST_P(NavigationPredictorBrowserTest, Pipeline) {
   }
 }
 
+// Test that no metrics are recorded in off-the-record profiles.
+IN_PROC_BROWSER_TEST_P(NavigationPredictorBrowserTest, PipelineOffTheRecord) {
+  base::HistogramTester histogram_tester;
+
+  const GURL& url = GetTestURL("/simple_page_with_anchors.html");
+  Browser* incognito = CreateIncognitoBrowser();
+  ui_test_utils::NavigateToURL(incognito, url);
+  base::RunLoop().RunUntilIdle();
+
+  histogram_tester.ExpectTotalCount(
+      "AnchorElementMetrics.Visible.NumberOfAnchorElements", 0);
+  histogram_tester.ExpectTotalCount(
+      "AnchorElementMetrics.Visible.NumberOfAnchorElementsAfterMerge", 0);
+}
+
 // Test that anchor elements within an iframe tagged as an ad are discarded when
 // predicting next navigation.
 IN_PROC_BROWSER_TEST_P(NavigationPredictorBrowserTest, PipelineAdsFrameTagged) {
@@ -226,6 +241,27 @@ IN_PROC_BROWSER_TEST_P(NavigationPredictorBrowserTest, ClickAnchorElement) {
   }
 }
 
+// Simulate a click at the anchor element in off-the-record profile. Metrics
+// should not be recorded.
+IN_PROC_BROWSER_TEST_P(NavigationPredictorBrowserTest,
+                       ClickAnchorElementOffTheRecord) {
+  base::HistogramTester histogram_tester;
+
+  const GURL& url = GetTestURL("/simple_page_with_anchors.html");
+
+  Browser* incognito = CreateIncognitoBrowser();
+  ui_test_utils::NavigateToURL(incognito, url);
+  base::RunLoop().RunUntilIdle();
+
+  EXPECT_TRUE(content::ExecuteScript(
+      incognito->tab_strip_model()->GetActiveWebContents(),
+      "document.getElementById('google').click();"));
+  base::RunLoop().RunUntilIdle();
+
+  histogram_tester.ExpectTotalCount(
+      "AnchorElementMetrics.Clicked.HrefEngagementScore2", 0);
+}
+
 // Simulate click at the anchor element.
 // Test that correct area ranks are recorded.
 IN_PROC_BROWSER_TEST_P(NavigationPredictorBrowserTest, AreaRank) {