Move about://-related constants from //content to //url

content/test/accessibility_browser_test_utils.cc

Index: content/test/accessibility_browser_test_utils.cc
diff --git a/content/test/accessibility_browser_test_utils.cc b/content/test/accessibility_browser_test_utils.cc
index dc7a7f853f8f70709cd9607dd28d52e1f985e9c6..ba0331c485fc84a0e910821e39473ee3d2dd3237 100644
--- a/content/test/accessibility_browser_test_utils.cc
+++ b/content/test/accessibility_browser_test_utils.cc
@@ -80,7 +80,7 @@ bool AccessibilityNotificationWaiter::IsAboutBlank() {
     if (root.string_attributes[i].first != ui::AX_ATTR_DOC_URL)
       continue;
     const std::string& doc_url = root.string_attributes[i].second;
-    return doc_url == kAboutBlankURL;
+    return doc_url == url::kAboutBlankURL;
   }
   return false;
 }