Precache should cancel when there is user traffic

chrome/browser/precache/precache_util.h

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_PRECACHE_PRECACHE_UTIL_H_
+#define CHROME_BROWSER_PRECACHE_PRECACHE_UTIL_H_
+
+namespace net {
+class URLRequest;
+}
+
+namespace precache {
+
+void UpdatePrecacheMetricsAndState(const net::URLRequest* request,
+                                   void* profile_id);
+
+}  // namespace precache
+
+#endif  // CHROME_BROWSER_PRECACHE_PRECACHE_UTIL_H_