Updating histograms to allow for experiments & log origin-based histograms.

chrome/browser/prerender/prerender_util.h

+// Copyright (c) 2011 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_PRERENDER_PRERENDER_UTIL_H_
+#define CHROME_BROWSER_PRERENDER_PRERENDER_UTIL_H_
+
+#include "base/basictypes.h"
+#include "googleurl/src/gurl.h"
+
+namespace prerender {
+
+// ID indicating that no experiment is active.
+const uint8 kNoExperiment = 0;
+
+// Extracts a urlencoded URL stored in a url= query parameter from a URL
+// supplied, if available, and stores it in alias_url.  Returns whether or not
+// the operation succeeded (i.e. a valid URL was found).
+bool MaybeGetQueryStringBasedAliasURL(const GURL& url, GURL* alias_url);
+
+// Extracts an experiment stored in the query parameter
+// lpe= from the URL supplied, and returns it.
+// Returns kNoExperiment if no experiment ID is found, or if the ID
+// is not an integer in the range 1 to 9.
+uint8 GetQueryStringBasedExperiment(const GURL& url);
+
+}  // namespace prerender
+
+#endif  // CHROME_BROWSER_PRERENDER_PRERENDER_UTIL_H_