Add the UMA recording recall of URLRequests preconnected.

chrome/browser/net/connect_interceptor.cc

Index: chrome/browser/net/connect_interceptor.cc
diff --git a/chrome/browser/net/connect_interceptor.cc b/chrome/browser/net/connect_interceptor.cc
index e2bf67b57e10e8499e4cb055accf32481e7e0a1f..2250b9938eaa175f304be57fb9c31fcebb5c5752 100644
--- a/chrome/browser/net/connect_interceptor.cc
+++ b/chrome/browser/net/connect_interceptor.cc
@@ -4,6 +4,7 @@
 
 #include "chrome/browser/net/connect_interceptor.h"
 
+#include "base/metrics/histogram.h"
 #include "chrome/browser/net/predictor.h"
 #include "net/base/load_flags.h"
 #include "net/url_request/url_request.h"
@@ -20,6 +21,8 @@ static const int kMaxUnusedSocketLifetimeSecondsWithoutAGet = 10;
 ConnectInterceptor::ConnectInterceptor(Predictor* predictor)
     : timed_cache_(base::TimeDelta::FromSeconds(
           kMaxUnusedSocketLifetimeSecondsWithoutAGet)),
+      recent_preconnects_(base::TimeDelta::FromSeconds(
+          kMaxUnusedSocketLifetimeSecondsWithoutAGet)),
       predictor_(predictor) {
   DCHECK(predictor);
 }
@@ -77,6 +80,9 @@ void ConnectInterceptor::WitnessURLRequest(net::URLRequest* request) const {
     }
   }
   timed_cache_.SetRecentlySeen(request_scheme_host);
+  UMA_HISTOGRAM_BOOLEAN(
+      "Net.PreconnectedNavigation",
+      recent_preconnects_.WasRecentlySeen(request_scheme_host));
 
   // Subresources for main frames usually get predicted when we detected the
   // main frame request - way back in RenderViewHost::Navigate.  So only handle
@@ -87,6 +93,11 @@ void ConnectInterceptor::WitnessURLRequest(net::URLRequest* request) const {
   return;
 }
 
+void ConnectInterceptor::WitnessPreconnect(const GURL& url) {
+  GURL request_scheme_host(Predictor::CanonicalizeUrl(url));
+  recent_preconnects_.SetRecentlySeen(request_scheme_host);

[mmenke, 2013/05/22 17:58:43]

I think this could actually all be done in the predictor more simply, since
|this| owns it.

[kouhei (in TOK), 2013/05/23 07:31:13]

I tried moving the logic to Predictor. TimedCache is also moved out from
ConnectInterceptor so that I can use it from Predictor too.

+}
+
 ConnectInterceptor::TimedCache::TimedCache(const base::TimeDelta& max_duration)
     : mru_cache_(UrlMruTimedCache::NO_AUTO_EVICT),
       max_duration_(max_duration) {