Use base::StringPairs where appropriate from src/ui

ui/accessibility/ax_node_data.h

Index: ui/accessibility/ax_node_data.h
diff --git a/ui/accessibility/ax_node_data.h b/ui/accessibility/ax_node_data.h
index cd30fbb2c06ae7ce903c1d73a535cba3b2b1076d..b6a1310ca1e5df0de29eb54a23daf886d52887c7 100644
--- a/ui/accessibility/ax_node_data.h
+++ b/ui/accessibility/ax_node_data.h
@@ -10,6 +10,7 @@
 #include <vector>
 
 #include "base/strings/string16.h"
+#include "base/strings/string_split.h"
 #include "ui/accessibility/ax_enums.h"
 #include "ui/accessibility/ax_export.h"
 #include "ui/gfx/rect.h"
@@ -52,7 +53,7 @@ struct AX_EXPORT AXNodeData {
   std::vector<std::pair<AXBoolAttribute, bool> > bool_attributes;
   std::vector<std::pair<AXIntListAttribute, std::vector<int32> > >
       intlist_attributes;
-  std::vector<std::pair<std::string, std::string> > html_attributes;
+  base::StringPairs html_attributes;
   std::vector<int32> child_ids;
 };