Add condition to avoid prefetching a change password URL if already available.

This CL adds a condition to avoid prefetching a change password URL for requested facet, if Affiliation Service already stores data for this facet from previous prefetch. The change affects WellKnownChangePasswordNavigationThrottle and saves time that would be spent on unnecessary prefetch.

Bug: 1108279
Change-Id: Idcab44f3a6a277298c97a0fdde6c6f6e88f40cec
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2443655
Commit-Queue: Viktor Semeniuk <vsemeniuk@google.com>
Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Reviewed-by: Vasilii Sukhanov <vasilii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825286}

chrome/browser/ui/passwords/well_known_change_password_navigation_throttle.cc

@@ -117,8 +117,10 @@ WellKnownChangePasswordNavigationThrottle::
     affiliation_service_ =
         AffiliationServiceFactory::GetForProfile(Profile::FromBrowserContext(
             handle->GetWebContents()->GetBrowserContext()));
-    well_known_change_password_state_.PrefetchChangePasswordURLs(
-        affiliation_service_, {request_url_});
+    if (affiliation_service_->GetChangePasswordURL(request_url_).is_empty()) {
+      well_known_change_password_state_.PrefetchChangePasswordURLs(
+          affiliation_service_, {request_url_});
+    }
   } else {
     change_password_url_service_ =
         ChangePasswordUrlServiceFactory::GetForBrowserContext(