Add successful request time histograms for both main frame and subresource loads.

Bug: None
Change-Id: I836fb3f2b238bc4d0e5cd1801452ee26027d4465
Reviewed-on: https://chromium-review.googlesource.com/800950Reviewed-by: Charlie Harrison <csharrison@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Charlie Harrison <csharrison@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520767}

content/browser/loader/resource_dispatcher_host_impl.cc

@@ -664,6 +664,9 @@ void ResourceDispatcherHostImpl::DidReceiveResponse(
 void ResourceDispatcherHostImpl::DidFinishLoading(ResourceLoader* loader) {
   ResourceRequestInfoImpl* info = loader->GetRequestInfo();
 
+  base::TimeDelta request_loading_time(base::TimeTicks::Now() -
+                                       loader->request()->creation_time());
+
   // Record final result of all resource loads.
   if (info->GetResourceType() == RESOURCE_TYPE_MAIN_FRAME) {
     // This enumeration has "3" appended to its name to distinguish it from
@@ -671,6 +674,10 @@ void ResourceDispatcherHostImpl::DidFinishLoading(ResourceLoader* loader) {
     UMA_HISTOGRAM_SPARSE_SLOWLY(
         "Net.ErrorCodesForMainFrame3",
         -loader->request()->status().error());
+    if (loader->request()->status().error() == net::OK) {
+      UMA_HISTOGRAM_LONG_TIMES("Net.RequestTime2Success.MainFrame",
+                               request_loading_time);
+    }
     if (loader->request()->status().error() == net::ERR_ABORTED) {
       UMA_HISTOGRAM_CUSTOM_COUNTS("Net.ErrAborted.SentBytes",
                                   loader->request()->GetTotalSentBytes(), 1,
@@ -699,6 +706,10 @@ void ResourceDispatcherHostImpl::DidFinishLoading(ResourceLoader* loader) {
           "Net.CertificateTransparency.MainFrameValidSCTCount", num_valid_scts);
     }
   } else {
+    if (loader->request()->status().error() == net::OK) {
+      UMA_HISTOGRAM_LONG_TIMES("Net.RequestTime2Success.Subresource",
+                               request_loading_time);
+    }
     if (info->GetResourceType() == RESOURCE_TYPE_IMAGE) {
       UMA_HISTOGRAM_SPARSE_SLOWLY(
           "Net.ErrorCodesForImages",

tools/metrics/histograms/histograms.xml

@@ -45733,6 +45733,22 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Net.RequestTime2Success.MainFrame">
+  <owner>csharrison@chromium.org</owner>
+  <summary>
+    The amount of time between request initiation and request completion for
+    success for main frame resources.
+  </summary>
+</histogram>
+
+<histogram name="Net.RequestTime2Success.Subresource">
+  <owner>csharrison@chromium.org</owner>
+  <summary>
+    The amount of time between request initiation and request completion for
+    success for non-main frame resources.
+  </summary>
+</histogram>
+
 <histogram name="Net.ResourceDispatcherHost.OutstandingRequests.PerProcess"
     units="requests">
   <owner>xunjieli@chromium.org</owner>