MD History: truncate title to 300 chars in C++ instead of JS

chrome/browser/ui/webui/uber/uber_ui_browsertest.cc

Index: chrome/browser/ui/webui/uber/uber_ui_browsertest.cc
diff --git a/chrome/browser/ui/webui/uber/uber_ui_browsertest.cc b/chrome/browser/ui/webui/uber/uber_ui_browsertest.cc
index ee94138b69e9e8a5913388c83399904572bdeeed..0b46b384c21578e93db33dc6ea762d16e1e3240a 100644
--- a/chrome/browser/ui/webui/uber/uber_ui_browsertest.cc
+++ b/chrome/browser/ui/webui/uber/uber_ui_browsertest.cc
@@ -13,6 +13,7 @@
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/tabs/tab_strip_model.h"
+#include "chrome/browser/ui/webui/md_history_ui.h"
 #include "chrome/common/chrome_features.h"
 #include "chrome/common/chrome_switches.h"
 #include "chrome/common/url_constants.h"
@@ -99,11 +100,7 @@ IN_PROC_BROWSER_TEST_F(UberUIBrowserTest, EnableMdExtensionsHidesExtensions) {
 }
 
 IN_PROC_BROWSER_TEST_F(UberUIBrowserTest, EnableMdHistoryHidesHistory) {
-  std::unique_ptr<base::FeatureList> feature_list(new base::FeatureList);
-  feature_list->InitializeFromCommandLine(
-      features::kMaterialDesignHistory.name, "");
-  base::FeatureList::ClearInstanceForTesting();
-  base::FeatureList::SetInstance(std::move(feature_list));
+  MdHistoryUI::SetEnabledForTesting(true);
 
   ui_test_utils::NavigateToURL(browser(), GURL(chrome::kChromeUIUberFrameURL));
   SelectTab();