Add browser test for WebUI URL logging

chrome/browser/ui/webui/log_web_ui_url.cc

 // Copyright 2015 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/ui/webui/log_web_ui_url.h"
 
+#include "base/bind.h"
 #include "base/hash.h"
 #include "base/metrics/histogram_base.h"
 #include "base/metrics/sparse_histogram.h"
 #include "chrome/common/url_constants.h"
 #include "content/public/common/url_constants.h"
 #include "url/gurl.h"
 
 #if defined(ENABLE_EXTENSIONS)
 #include "chrome/common/extensions/extension_constants.h"
 #include "extensions/common/constants.h"
 #endif
 
 namespace webui {
 
+namespace {
+
+static WebUIUrlHash* g_hash = nullptr;

[Dan Beam, 2015/09/26 23:02:14]

if you have any suggestions that don't require this g_* pointer and manual
delete to allow tests to spy here, I'm all ears.

note: this needs to be changed for the chrome/ level, not just content/, afaik
(otherwise I'd just call SetContentBrowserClientForTesting() or whatever)

+
+uint32 DefaultHash(const GURL& web_ui_url) {
+  return base::Hash(web_ui_url.spec());
+}
+
+}  // namespace
+
 bool LogWebUIUrl(const GURL& web_ui_url) {
   bool should_log = web_ui_url.SchemeIs(content::kChromeUIScheme) ||
                     web_ui_url.SchemeIs(content::kChromeDevToolsScheme);
 
 #if defined(ENABLE_EXTENSIONS)
   if (web_ui_url.SchemeIs(extensions::kExtensionScheme))
     should_log = web_ui_url.host() == extension_misc::kBookmarkManagerId;
 #endif
 
   if (should_log) {
-    uint32 hash = base::Hash(web_ui_url.GetOrigin().spec());
+    if (!g_hash)
+      g_hash = new WebUIUrlHash(base::Bind(DefaultHash));
+
+    uint32 hash = g_hash->Run(web_ui_url.GetOrigin());
     UMA_HISTOGRAM_SPARSE_SLOWLY("WebUI.CreatedForUrl",
                                 static_cast<base::HistogramBase::Sample>(hash));
   }
 
   return should_log;
 }
 
+void SetHashFunctionForTesting(const WebUIUrlHash& testing_hash) {
+  if (g_hash) {
+    delete g_hash;
+    g_hash = nullptr;
+  }
+
+  if (!testing_hash.is_null())
+    g_hash = new WebUIUrlHash(testing_hash);
+}
+
 }  // namespace webui