Update main frame status in PrefetchPorxy UKM logs when probing is disabled.

Bug: 1163983
Change-Id: Ic16c8a3015d29df741fbd50b4496205255bc5512
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2618541
Commit-Queue: Simon Pelchat <spelchat@chromium.org>
Auto-Submit: Simon Pelchat <spelchat@chromium.org>
Reviewed-by: Robert Ogden <robertogden@chromium.org>
Cr-Commit-Position: refs/heads/master@{#841705}

chrome/browser/prefetch/prefetch_proxy/prefetch_proxy_browsertest.cc

@@ -1339,10 +1339,11 @@ IN_PROC_BROWSER_TEST_F(PrefetchProxyBrowserTest,
               {"DataLength", 0},                    /* only checked for > 0 */
               {"FetchDurationMS", 0},               /* only checked for > 0 */
               {"NavigationStartToFetchStartMS", 0}, /* only checked for > 0 */
+              {"ISPFilteringStatus", 0},
               {"LinkClicked", 1},
               {"LinkPosition", 1},
               {"ResourceType", 1},
-              {"Status", 14},
+              {"Status", 0},
           }},
       // not eligible url #1
       UkmEntry{srp_source_id,

chrome/browser/prefetch/prefetch_proxy/prefetch_proxy_url_loader_interceptor.cc

@@ -182,6 +182,10 @@ void PrefetchProxyURLLoaderInterceptor::MaybeCreateLoader(
                        std::move(on_success_callback)));
     return;
   }
+  // Inform the metrics collector that the main frame HTML was used and probing
+  // was disabled.
+  ReportProbeResult(frame_tree_node_id_, url_,
+                    PrefetchProxyProbeResult::kNoProbing);
 
   EnsureCookiesCopiedAndInterceptPrefetchedNavigation(
       tentative_resource_request, std::move(prefetch));