Add the UMA recording recall of URLRequests preconnected.

chrome/browser/net/connect_interceptor.h

Index: chrome/browser/net/connect_interceptor.h
diff --git a/chrome/browser/net/connect_interceptor.h b/chrome/browser/net/connect_interceptor.h
index 3372ad81e714bdbd0a2508f1fe5550d675edbd47..00b9ef1cef5ecb286208f18e1b96a8e5d17bbb3d 100644
--- a/chrome/browser/net/connect_interceptor.h
+++ b/chrome/browser/net/connect_interceptor.h
@@ -33,6 +33,8 @@ class ConnectInterceptor {
   // Learn about referrers, and optionally preconnect based on history.
   void WitnessURLRequest(net::URLRequest* request) const;
 
+  void WitnessPreconnect(const GURL& url);
+
  private:
   // Provide access to local class TimedCache for testing.
   FRIEND_TEST_ALL_PREFIXES(ConnectInterceptorTest, TimedCacheRecall);
@@ -71,6 +73,7 @@ class ConnectInterceptor {
     DISALLOW_COPY_AND_ASSIGN(TimedCache);
   };
   TimedCache timed_cache_;
+  TimedCache recent_preconnects_;
   Predictor* const predictor_;
 
   DISALLOW_COPY_AND_ASSIGN(ConnectInterceptor);