[page_load_metrics] Add a NavigationThrottle for richer abort metrics

content/browser/frame_host/navigation_controller_impl_browsertest.cc

Index: content/browser/frame_host/navigation_controller_impl_browsertest.cc
diff --git a/content/browser/frame_host/navigation_controller_impl_browsertest.cc b/content/browser/frame_host/navigation_controller_impl_browsertest.cc
index 9aacb49b0e91ef4143019bde521851eae795c131..84f08ee8e292e7affe4c7c6ec03e90b8ecbb2d53 100644
--- a/content/browser/frame_host/navigation_controller_impl_browsertest.cc
+++ b/content/browser/frame_host/navigation_controller_impl_browsertest.cc
@@ -1868,7 +1868,7 @@ IN_PROC_BROWSER_TEST_F(NavigationControllerBrowserTest,
                          "document.body.appendChild(iframe);";
     EXPECT_TRUE(ExecuteScript(root, script));
   }
-  subframe_delayer.WaitForWillStartRequest();
+  EXPECT_TRUE(subframe_delayer.WaitForWillStartRequest());
 
   // Stop the request so that we can wait for load stop below, without ending up
   // with a commit for this frame.
@@ -4059,7 +4059,7 @@ IN_PROC_BROWSER_TEST_F(NavigationControllerBrowserTest,
   // second page, though, causes it to do a replaceState().
   TestNavigationManager manager(shell()->web_contents(), start_url);
   controller.GoBack();
-  manager.WaitForWillStartRequest();
+  EXPECT_TRUE(manager.WaitForWillStartRequest());
 
   // The navigation that just happened was the replaceState(), which should not
   // have changed the position into the navigation entry list. Make sure that
@@ -4982,9 +4982,9 @@ IN_PROC_BROWSER_TEST_F(NavigationControllerBrowserTest,
       frame_url_a2);
   TestNavigationManager mainframe_delayer(shell()->web_contents(), url_b);
   controller.GoForward();
-  subframe_delayer.WaitForWillStartRequest();
+  EXPECT_TRUE(subframe_delayer.WaitForWillStartRequest());
   controller.GoForward();
-  mainframe_delayer.WaitForWillStartRequest();
+  EXPECT_TRUE(mainframe_delayer.WaitForWillStartRequest());
   EXPECT_EQ(2, controller.GetPendingEntryIndex());
 
   // Let the subframe commit.