[page_load_metrics] use data from WebContents::GetOpener

components/page_load_metrics/browser/metrics_web_contents_observer.cc

Index: components/page_load_metrics/browser/metrics_web_contents_observer.cc
diff --git a/components/page_load_metrics/browser/metrics_web_contents_observer.cc b/components/page_load_metrics/browser/metrics_web_contents_observer.cc
index 540646e5dbc58ebf2c742a523d8a2df364d11b86..54a9587ec2ea1d9e7e58fb47a2338c0cd67aa85b 100644
--- a/components/page_load_metrics/browser/metrics_web_contents_observer.cc
+++ b/components/page_load_metrics/browser/metrics_web_contents_observer.cc
@@ -208,7 +208,7 @@ void LogAbortChainSameURLHistogram(int aborted_chain_size_same_url) {
 PageLoadTracker::PageLoadTracker(
     bool in_foreground,
     PageLoadMetricsEmbedderInterface* embedder_interface,
-    PageLoadTracker* const currently_committed_load_or_null,
+    const GURL& currently_committed_url,
     content::NavigationHandle* navigation_handle,
     int aborted_chain_size,
     int aborted_chain_size_same_url)
@@ -222,10 +222,6 @@ PageLoadTracker::PageLoadTracker(
       embedder_interface_(embedder_interface) {
   DCHECK(!navigation_handle->HasCommitted());
   embedder_interface_->RegisterObservers(this);
-  const GURL& currently_committed_url =
-      currently_committed_load_or_null
-          ? currently_committed_load_or_null->committed_url()
-          : GURL::EmptyGURL();
   for (const auto& observer : observers_) {
     observer->OnStart(navigation_handle, currently_committed_url);
   }
@@ -462,7 +458,8 @@ MetricsWebContentsObserver::MetricsWebContentsObserver(
     std::unique_ptr<PageLoadMetricsEmbedderInterface> embedder_interface)
     : content::WebContentsObserver(web_contents),
       in_foreground_(false),
-      embedder_interface_(std::move(embedder_interface)) {}
+      embedder_interface_(std::move(embedder_interface)),
+      has_navigated_(false) {}
 
 MetricsWebContentsObserver* MetricsWebContentsObserver::CreateForWebContents(
     content::WebContents* web_contents,
@@ -501,6 +498,8 @@ void MetricsWebContentsObserver::DidStartNavigation(
     return;
   if (embedder_interface_->IsPrerendering(web_contents()))
     return;
+  if (navigation_handle->GetURL().spec().compare(url::kAboutBlankURL) == 0)

[Bryan McQuade, 2016/04/26 19:43:31]

seems like a good addition, thanks!

+    return;
 
   std::unique_ptr<PageLoadTracker> last_aborted =
       NotifyAbortedProvisionalLoadsNewNavigation(navigation_handle);
@@ -517,6 +516,21 @@ void MetricsWebContentsObserver::DidStartNavigation(
     chain_size = last_aborted->aborted_chain_size() + 1;
   }
 
+  // Pass in the last committed url to the PageLoadTracker. This is used for

[Bryan McQuade, 2016/04/26 19:43:31]

let's leave out the 'this is used for FromGWS metrics' since other observers may
start using it at which point the comment becomes a bit stale. we're making this
a first class part of the observer API so I think we should assume that any
observer may start using this data.

[Charlie Harrison, 2016/04/26 20:37:29]

Done.

+  // FromGWS metrics. If the MWCO has never observed a committed load, use the
+  // last committed url from this WebContent's opener. This is more accurate
+  // than using referrers due to referrer sanitizing and origin referrers. Note
+  // that this could potentially be inaccurate if the opener has since
+  // navigated.
+  content::WebContents* opener = web_contents()->GetOpener();
+  const GURL& opener_url =
+      !has_navigated_ && opener
+          ? web_contents()->GetOpener()->GetLastCommittedURL()
+          : GURL::EmptyGURL();
+  const GURL currently_committed_url =

[Bryan McQuade, 2016/04/26 19:43:31]

oh, looks like this might still need to be updated to const GURL&

[Charlie Harrison, 2016/04/26 20:37:29]

Done. Sorry.

+      committed_load_ ? committed_load_->committed_url() : opener_url;
+  has_navigated_ = true;
+
   // We can have two provisional loads in some cases. E.g. a same-site
   // navigation can have a concurrent cross-process navigation started
   // from the omnibox.
@@ -528,7 +542,7 @@ void MetricsWebContentsObserver::DidStartNavigation(
   provisional_loads_.insert(std::make_pair(
       navigation_handle,
       base::WrapUnique(new PageLoadTracker(
-          in_foreground_, embedder_interface_.get(), committed_load_.get(),
+          in_foreground_, embedder_interface_.get(), currently_committed_url,
           navigation_handle, chain_size, chain_size_same_url))));
 }