Revert "Don't adjust the NavigationTimings on redirects"

This reverts commit aeecb4f3.

Reason for revert: Causing lots of failures on webkit bots, e.g.:
https://ci.chromium.org/buildbot/chromium.webkit/WebKit%20Linux%20Trusty/42143

Original change's description:
> Don't adjust the NavigationTimings on redirects
> 
> We adjust the timings in WebDocumentLoaderImpl::UpdateNavigation(),
> shouldn't update in each AddRedirect() (which is called in a batch
> way after all the redirects are handled in the browser process with PlzNavigate,
> adjusting timings there with current timestamp is totally wrong)
> 
> R=​ksakamoto,arthursonzogni
> 
> Bug: 813889
> Change-Id: I3a57d3fdf1833c300feb5ee61737b64cece0946b
> Reviewed-on: https://chromium-review.googlesource.com/974673
> Reviewed-by: Kunihiko Sakamoto <ksakamoto@chromium.org>
> Commit-Queue: Kinuko Yasuda <kinuko@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#546001}

TBR=kinuko@chromium.org,ksakamoto@chromium.org,arthursonzogni@chromium.org

Change-Id: I467ed888084ea0eda06faa903d1797fabffc47da
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 813889
Reviewed-on: https://chromium-review.googlesource.com/981912Reviewed-by: Ben Wells <benwells@chromium.org>
Commit-Queue: Ben Wells <benwells@chromium.org>
Cr-Commit-Position: refs/heads/master@{#546025}

third_party/WebKit/LayoutTests/external/wpt/navigation-timing/test_timing_server_redirect.html

@@ -32,7 +32,6 @@
                 test_timing_order('redirectStart', 'navigationStart');
                 test_timing_order('redirectEnd', 'redirectStart');
                 test_timing_order('fetchStart', 'redirectEnd');
-                test_timing_order('requestStart', 'fetchStart');
             }
         </script>
 

third_party/WebKit/Source/core/loader/DocumentLoadTiming.cpp

@@ -137,9 +137,10 @@ void DocumentLoadTiming::SetNavigationStart(TimeTicks navigation_start) {
 void DocumentLoadTiming::AddRedirect(const KURL& redirecting_url,
                                      const KURL& redirected_url) {
   redirect_count_++;
-
-  // Note: we update load timings for redirects in WebDocumentLoaderImpl::
-  // UpdateNavigation, hence updating no timings here.
+  if (redirect_start_.is_null())
+    SetRedirectStart(fetch_start_);
+  MarkRedirectEnd();
+  MarkFetchStart();
 
   // Check if the redirected url is allowed to access the redirecting url's
   // timing information.