PlzNavigate: Refactor unit test helper functions

content/browser/frame_host/navigator_impl.h

Index: content/browser/frame_host/navigator_impl.h
diff --git a/content/browser/frame_host/navigator_impl.h b/content/browser/frame_host/navigator_impl.h
index e142b3fd1ffddc0178aec59e92aae5a7f8f3348c..8618e0f9232311c6211088242963eae870cd2a1e 100644
--- a/content/browser/frame_host/navigator_impl.h
+++ b/content/browser/frame_host/navigator_impl.h
@@ -82,11 +82,16 @@ class CONTENT_EXPORT NavigatorImpl : public Navigator {
       const base::TimeTicks& renderer_before_unload_end_time) override;
   void CancelNavigation(FrameTreeNode* frame_tree_node) override;
 
+  // PlzNavigate
+  // Returns the navigation request for a given node. Used in tests.
+  NavigationRequest* GetNavigationRequestForNodeForTesting(
+      FrameTreeNode* frame_tree_node);
+
  private:
   // Holds data used to track browser side navigation metrics.
   struct NavigationMetricsData;
 
-  friend class NavigatorTest;
+  friend class NavigatorTestWithBrowserSideNavigation;
   ~NavigatorImpl() override;
 
   // Navigates to the given entry, which must be the pending entry.  Private