Override noise provider in HeavyAd tests where there is no heavy ad

crrrev.com/c/1846313 added noise to the network threshold for heavy ads. This
change did not override the noise provider in
AdsPageLoadMetricsObserverTest.HeavyAdWithUserGesture_NotConsideredHeavy, This
does not break the test because we never consider the ad to be heavy. However, if
there was a regression that caused an ad with a user gesture to be considered heavy,
this test becomes non-determinstic as the noise may cause us to not label it as
heavy.

This CL mocks the noise provider to 0 to ensure we are testing the user gesture logic
correctly. This similar behavior was seen in two other tests which are also updated.

Change-Id: I7f085800b6ae189a5082c207460defd68b371638
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1849130
Commit-Queue: John Delaney <johnidel@chromium.org>
Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Cr-Commit-Position: refs/heads/master@{#706672}

chrome/browser/page_load_metrics/observers/ad_metrics/ads_page_load_metrics_observer_unittest.cc

@@ -579,7 +579,13 @@ class AdsPageLoadMetricsObserverTest
     auto observer = std::make_unique<AdsPageLoadMetricsObserver>(
         clock_.get(), test_blocklist_.get());
     ads_observer_ = observer.get();
+
+    // Mock the noise provider to make tests deterministic. Tests can override
+    // this again to test non-zero noise.
+    ads_observer_->SetHeavyAdThresholdNoiseProviderForTesting(
+        std::make_unique<MockNoiseProvider>(0 /* noise */));
     tracker->AddObserver(std::move(observer));
+
     // Swap out the ui::ScopedVisibilityTracker to use the test clock.
     if (clock_) {
       ui::ScopedVisibilityTracker visibility_tracker(clock_.get(), true);
@@ -1671,10 +1677,6 @@ TEST_F(AdsPageLoadMetricsObserverTest, HeavyAdFeatureOff_UMARecorded) {
   OverrideVisibilityTrackerWithMockClock();
 
   RenderFrameHost* main_frame = NavigateMainFrame(kNonAdUrl);
-
-  OverrideHeavyAdNoiseProvider(
-      std::make_unique<MockNoiseProvider>(0 /* network noise */));
-
   RenderFrameHost* ad_frame_none =
       CreateAndNavigateSubFrame(kAdUrl, main_frame);
   RenderFrameHost* ad_frame_net = CreateAndNavigateSubFrame(kAdUrl, main_frame);
@@ -1741,9 +1743,6 @@ TEST_F(AdsPageLoadMetricsObserverTest, HeavyAdNetworkUsage_InterventionFired) {
   feature_list.InitAndEnableFeature(features::kHeavyAdIntervention);
 
   RenderFrameHost* main_frame = NavigateMainFrame(kNonAdUrl);
-
-  OverrideHeavyAdNoiseProvider(
-      std::make_unique<MockNoiseProvider>(0 /* network noise */));
   RenderFrameHost* ad_frame = CreateAndNavigateSubFrame(kAdUrl, main_frame);
 
   // Load just under the threshold amount of bytes.
@@ -2003,9 +2002,6 @@ TEST_F(AdsPageLoadMetricsObserverTest,
     blocklist()->AddEntry(GURL(kNonAdUrl).host(), true, 0);
 
   RenderFrameHost* main_frame = NavigateMainFrame(kNonAdUrl);
-
-  OverrideHeavyAdNoiseProvider(
-      std::make_unique<MockNoiseProvider>(0 /* network noise */));
   RenderFrameHost* ad_frame = CreateAndNavigateSubFrame(kAdUrl, main_frame);
 
   // Add enough data to trigger the intervention.
@@ -2034,9 +2030,6 @@ TEST_F(AdsPageLoadMetricsObserverTest, HeavyAdBlocklist_InterventionReported) {
     blocklist()->AddEntry(GURL(kNonAdUrl).host(), true, 0);
 
   RenderFrameHost* main_frame = NavigateMainFrame(kNonAdUrl);
-
-  OverrideHeavyAdNoiseProvider(
-      std::make_unique<MockNoiseProvider>(0 /* network noise */));
   RenderFrameHost* ad_frame = CreateAndNavigateSubFrame(kAdUrl, main_frame);
 
   // Add enough data to trigger the intervention.