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

chrome/browser/prerender/prerender_util.cc

Index: chrome/browser/prerender/prerender_util.cc
===================================================================
--- chrome/browser/prerender/prerender_util.cc	(revision 0)
+++ chrome/browser/prerender/prerender_util.cc	(revision 0)
@@ -0,0 +1,64 @@
+// 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.
+
+#include "chrome/browser/prerender/prerender_util.h"
+
+#include "base/logging.h"
+#include "googleurl/src/url_canon.h"
+#include "googleurl/src/url_parse.h"
+#include "googleurl/src/url_util.h"
+
+namespace prerender {
+
+bool MaybeGetQueryStringBasedAliasURL(
+    const GURL& url, GURL* alias_url) {
+  DCHECK(alias_url);
+  url_parse::Parsed parsed;
+  url_parse::ParseStandardURL(url.spec().c_str(), url.spec().length(),
+                              &parsed);
+  url_parse::Component query = parsed.query;
+  url_parse::Component key, value;
+  while (url_parse::ExtractQueryKeyValue(url.spec().c_str(), &query, &key,
+                                         &value)) {
+    if (key.len != 3 || strncmp(url.spec().c_str() + key.begin, "url", key.len))
+      continue;
+    // We found a url= query string component.
+    if (value.len < 1)
+      continue;
+    url_canon::RawCanonOutputW<1024> decoded_url;
+    url_util::DecodeURLEscapeSequences(url.spec().c_str() + value.begin,
+                                       value.len, &decoded_url);
+    GURL new_url(string16(decoded_url.data(), decoded_url.length()));
+    if (!new_url.is_empty() && new_url.is_valid()) {
+      *alias_url = new_url;
+      return true;
+    }
+    return false;
+  }
+  return false;
+}
+
+uint8 GetQueryStringBasedExperiment(const GURL& url) {
+  url_parse::Parsed parsed;
+  url_parse::ParseStandardURL(url.spec().c_str(), url.spec().length(),
+                              &parsed);
+  url_parse::Component query = parsed.query;
+  url_parse::Component key, value;
+  while (url_parse::ExtractQueryKeyValue(url.spec().c_str(), &query, &key,
+                                         &value)) {
+    if (key.len != 3 || strncmp(url.spec().c_str() + key.begin, "lpe", key.len))
+      continue;
+
+    // We found a lpe= query string component.
+    if (value.len != 1)
+      continue;
+    uint8 exp = *(url.spec().c_str() + value.begin) - '0';
+    if (exp < 1 || exp > 9)
+      continue;
+    return exp;
+  }
+  return kNoExperiment;
+}
+
+}  // namespace prerender