Add browser test for WebUI URL logging

chrome/browser/ui/webui/log_web_ui_url.cc

Index: chrome/browser/ui/webui/log_web_ui_url.cc
diff --git a/chrome/browser/ui/webui/log_web_ui_url.cc b/chrome/browser/ui/webui/log_web_ui_url.cc
index 3b793a211879fecf1fcad90fa6f2fa1fc6a417a6..245b4f3a782ec1ac76ef4b145b406cc454718d54 100644
--- a/chrome/browser/ui/webui/log_web_ui_url.cc
+++ b/chrome/browser/ui/webui/log_web_ui_url.cc
@@ -4,6 +4,7 @@
 
 #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"
@@ -18,6 +19,16 @@
 
 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);
@@ -28,7 +39,10 @@ bool LogWebUIUrl(const GURL& web_ui_url) {
 #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));
   }
@@ -36,4 +50,14 @@ bool LogWebUIUrl(const GURL& web_ui_url) {
   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