Add time-to-network histogram considering browser side navigation

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 ebfce6cdca9ef6cb37e6bf14c1dbb9cd11968d4f..2533241b5be46d2c389376987947d75083015fe7 100644
--- a/content/browser/loader/resource_dispatcher_host_impl.cc
+++ b/content/browser/loader/resource_dispatcher_host_impl.cc
@@ -32,6 +32,7 @@
 #include "content/browser/download/save_file_resource_handler.h"
 #include "content/browser/fileapi/chrome_blob_storage_context.h"
 #include "content/browser/frame_host/navigation_request_info.h"
+#include "content/browser/frame_host/navigator.h"
 #include "content/browser/loader/async_resource_handler.h"
 #include "content/browser/loader/buffered_resource_handler.h"
 #include "content/browser/loader/cross_site_resource_handler.h"
@@ -329,6 +330,24 @@ void AttachRequestBodyBlobDataHandles(
   }
 }
 
+// PlzNavigate
+// This method is called in the UI thread to send the timestamp of a resource
+// request to the respective NavigatorImpl (for an UMA histogram).
+void LogResourceRequestTimeOnUI(
+    base::TimeTicks timestamp,
+    int render_process_id,
+    int render_frame_host,
+    GURL url) {

[davidben, 2014/09/19 21:52:45]

Nit: const GURL& url

[carlosk, 2014/09/23 17:02:57]

Done.

+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  RenderFrameHostImpl* host =
+      RenderFrameHostImpl::FromID(render_process_id, render_frame_host);
+  if (host != NULL) {
+    DCHECK(host->frame_tree_node()->IsMainFrame());
+    content::Navigator* navigator = host->frame_tree_node()->navigator();

[clamy, 2014/09/19 14:56:03]

content:: is unnecessary here.

[carlosk, 2014/09/23 17:02:57]

Done.

+    navigator->LogResourceRequestTime(timestamp, url);
+  }
+}
+
 }  // namespace
 
 // static
@@ -888,6 +907,17 @@ void ResourceDispatcherHostImpl::OnRequestResource(
     int routing_id,
     int request_id,
     const ResourceHostMsg_Request& request_data) {
+  if (request_data.resource_type == RESOURCE_TYPE_MAIN_FRAME) {
+    int child_id = filter_->child_id();

[clamy, 2014/09/19 14:56:03]

nit: you could just write filter_->child_id() in the PostTask below.

[carlosk, 2014/09/23 17:02:57]

Done.

+    BrowserThread::PostTask(
+        BrowserThread::UI,
+        FROM_HERE,
+        base::Bind(&LogResourceRequestTimeOnUI,
+                   TimeTicks::Now(),

[davidben, 2014/09/19 21:52:45]

A thought: net/ maintains a net::LoadTimingInfo which already has a
request_start in it. It's not quite the same; that measures when //net starts
processing the request so it wouldn't include, say, SafeBrowsing checks.
net::LoadTiming is on the content::ResourceResponse. I wonder if it would be
better to extract it from there. In https://codereview.chromium.org/519533002/,
it'll be available on the ResourceResponse we get back when the navigation
commits.

https://code.google.com/p/chromium/codesearch#chromium/src/net/base/load_timi...

(It would also be easy enough for NavigationURLLoader to send this variant of
request_start through its Delegate, but this one means not introducing a new
variant.)

[carlosk, 2014/09/23 17:02:57]

As discussed in yesterday's hangout I'll use this information instead of the
more convoluted way it's done now. That means that for adding the
time-to-network histogram I'll wait on the CL 
https://codereview.chromium.org/519533002/ to be submitted so that the
request_time is made available at navigation commit.

[clamy, 2014/09/23 21:54:07]

As mentioned in the bug, this is problematic as
https://codereview.chromium.org/519533002/ will only make it available for the
PlzNavigate architecture. But this TimeToNetwork histogram is mostly interesting
for the current architecture, where we should see a significant delay on
Android. Therefore, we should have a solution that works in the current version
of the code as well.

+                   child_id,
+                   request_data.render_frame_id,
+                   request_data.url));
+  }
   BeginRequest(request_id, request_data, NULL, routing_id);
 }