Convert OverscrollNavigationOverlayTest.ImmediateLoadOnNavigate to use the new navigation callbacks…

content/browser/web_contents/aura/overscroll_navigation_overlay_unittest.cc

Index: content/browser/web_contents/aura/overscroll_navigation_overlay_unittest.cc
diff --git a/content/browser/web_contents/aura/overscroll_navigation_overlay_unittest.cc b/content/browser/web_contents/aura/overscroll_navigation_overlay_unittest.cc
index 771b042ad997cf4949f495ede0337f4371d965ed..7263fb2e79c77c2191ad46b03694d9a463e86c7d 100644
--- a/content/browser/web_contents/aura/overscroll_navigation_overlay_unittest.cc
+++ b/content/browser/web_contents/aura/overscroll_navigation_overlay_unittest.cc
@@ -40,11 +40,22 @@ class ImmediateLoadObserver : WebContentsObserver {
   }
   ~ImmediateLoadObserver() override {}
 
+  // TODO: remove this method when PlzNavigate is turned on by default.
   void DidStartNavigationToPendingEntry(const GURL& url,
                                         ReloadType reload_type) override {
-    // Simulate immediate web page load.
-    contents_->TestSetIsLoading(false);
-    Observe(nullptr);
+    if (!IsBrowserSideNavigationEnabled()) {
+      // Simulate immediate web page load.
+      contents_->TestSetIsLoading(false);
+      Observe(nullptr);
+    }
+  }
+
+  void DidStartNavigation(NavigationHandle* navigation_handlee) override {
+    if (IsBrowserSideNavigationEnabled()) {
+      // Simulate immediate web page load.
+      contents_->TestSetIsLoading(false);
+      Observe(nullptr);
+    }
   }
 
  private: