Add metrics for calculating precision/recall of link navigation pre-connect triggers.

chrome/browser/renderer_host/chrome_render_message_filter.cc

Index: chrome/browser/renderer_host/chrome_render_message_filter.cc
diff --git a/chrome/browser/renderer_host/chrome_render_message_filter.cc b/chrome/browser/renderer_host/chrome_render_message_filter.cc
index 56806a6a125c8688c275ed17da0686f9eab6b429..cfeafe0e02f4e4b88f0bb4669d6ab9aa5cc0ac06 100644
--- a/chrome/browser/renderer_host/chrome_render_message_filter.cc
+++ b/chrome/browser/renderer_host/chrome_render_message_filter.cc
@@ -193,9 +193,16 @@ void ChromeRenderMessageFilter::OnDnsPrefetch(
 }
 
 void ChromeRenderMessageFilter::OnPreconnect(const GURL& url) {
-  if (profile_->GetNetworkPredictor())
+  if (profile_->GetNetworkPredictor()) {
+    BrowserThread::PostTask(
+        BrowserThread::IO,
+        FROM_HERE,
+        base::Bind(&chrome_browser_net::Predictor::RecordPreconnectTrigger,
+                   base::Unretained(profile_->GetNetworkPredictor()),
+                   url));
     profile_->GetNetworkPredictor()->PreconnectUrl(
         url, GURL(), chrome_browser_net::UrlInfo::EARLY_LOAD_MOTIVATED, 1);
+  }
 }
 
 void ChromeRenderMessageFilter::OnResourceTypeStats(