PlzNavigate: improve bf navigations metrics

This CL improves the metrics landed in
https://codereview.chromium.org/2930353005/. It ensures timing metrics
are not recorded for same-document navigations. It also ensures that the
cache flag metric is not captured twice when PlzNavigate is enabled.

BUG=705559
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2944033002
Cr-Commit-Position: refs/heads/master@{#480853}

content/browser/frame_host/navigation_handle_impl.cc

@@ -715,7 +715,7 @@ void NavigationHandleImpl::ReadyToCommitNavigation(
   ready_to_commit_time_ = base::TimeTicks::Now();
 
   // For back-forward navigations, record metrics.
-  if (transition_ & ui::PAGE_TRANSITION_FORWARD_BACK) {
+  if ((transition_ & ui::PAGE_TRANSITION_FORWARD_BACK) && !IsSameDocument()) {
     bool is_same_process =
         render_frame_host_->GetProcess()->GetID() ==
         frame_tree_node_->current_frame_host()->GetProcess()->GetID();
@@ -756,7 +756,7 @@ void NavigationHandleImpl::DidCommitNavigation(
 
   // For back-forward navigations, record metrics.
   if ((transition_ & ui::PAGE_TRANSITION_FORWARD_BACK) &&
-      !ready_to_commit_time_.is_null()) {
+      !ready_to_commit_time_.is_null() && !IsSameDocument()) {
     UMA_HISTOGRAM_TIMES("Navigation.BackForward.ReadyToCommitUntilCommit",
                         base::TimeTicks::Now() - ready_to_commit_time_);
   }

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().SchemeIsHTTPOrHTTPS()) {
     LogBackForwardNavigationFlagsHistogram(request->load_flags());
   }
 

content/browser/loader/resource_loader.cc

@@ -645,7 +645,7 @@ void ResourceLoader::CompleteResponseStarted() {
   // of PLT for b/f navigations in PlzNavigate.
   if ((info->GetPageTransition() & ui::PAGE_TRANSITION_FORWARD_BACK) &&
       IsResourceTypeFrame(info->GetResourceType()) &&
-      !request_->url().SchemeIsBlob()) {
+      request_->url().SchemeIsHTTPOrHTTPS()) {
     UMA_HISTOGRAM_BOOLEAN("Navigation.BackForward.WasCached",
                           request_->was_cached());
   }