Add the UMA recording recall of URLRequests preconnected.

chrome/browser/net/timed_cache.cc

+// Copyright 2013 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.
+
+#include "chrome/browser/net/timed_cache.h"
+
+#include "googleurl/src/gurl.h"
+
+namespace chrome_browser_net {
+
+TimedCache::TimedCache(const base::TimeDelta& max_duration)
+    : mru_cache_(UrlMruTimedCache::NO_AUTO_EVICT),
+      max_duration_(max_duration) {
+}
+
+// Make Clang compilation happy with explicit destructor.
+TimedCache::~TimedCache() {}
+
+bool TimedCache::WasRecentlySeen(const GURL& url) {
+  DCHECK_EQ(url.GetWithEmptyPath(), url);
+  // Evict any overly old entries.
+  base::TimeTicks now = base::TimeTicks::Now();
+  UrlMruTimedCache::reverse_iterator eldest = mru_cache_.rbegin();
+  while (!mru_cache_.empty()) {
+    DCHECK(eldest == mru_cache_.rbegin());
+    if (now - eldest->second < max_duration_)
+      break;
+    eldest = mru_cache_.Erase(eldest);
+  }
+  return mru_cache_.end() != mru_cache_.Peek(url);
+}
+
+void TimedCache::SetRecentlySeen(const GURL& url) {
+  DCHECK_EQ(url.GetWithEmptyPath(), url);
+  mru_cache_.Put(url, base::TimeTicks::Now());
+}
+
+}  // namespace chrome_browser_net