PlzNavigate: improve bf navigations metrics

content/browser/loader/resource_dispatcher_host_impl.cc

Index: content/browser/loader/resource_dispatcher_host_impl.cc
diff --git a/content/browser/loader/resource_dispatcher_host_impl.cc b/content/browser/loader/resource_dispatcher_host_impl.cc
index 39108877eb551027f55ebfd7e6d29a13dc89690d..06102974a848242a356a30ca5c0138170a706a98 100644
--- a/content/browser/loader/resource_dispatcher_host_impl.cc
+++ b/content/browser/loader/resource_dispatcher_host_impl.cc
@@ -2240,7 +2240,8 @@ void ResourceDispatcherHostImpl::BeginRequestInternal(
   // TODO(clamy): Remove this once we understand the reason behind the
   // back-forward PLT regression with PlzNavigate
   if ((info->GetPageTransition() & ui::PAGE_TRANSITION_FORWARD_BACK) &&
-      IsResourceTypeFrame(info->GetResourceType())) {
+      IsResourceTypeFrame(info->GetResourceType()) &&
+      !request->url().SchemeIsBlob()) {

[nasko, 2017/06/19 18:16:55]

Maybe we can log these only for http/https cases, since other schemes are
unlikely to hit the network. I also think the page load metrics code only
considers http/https, so it will be more consistent with those?

If you end up changing this one, then it will be good to keep it in sync with
the other histogram added in resource_loader.cc.

[clamy, 2017/06/20 15:14:35]

Done.

     LogBackForwardNavigationFlagsHistogram(request->load_flags());
   }