Moved/renamed EscapeString from visual_studio_writer to XmlEscape in xml_element_writer.

tools/gn/visual_studio_writer.cc

Index: tools/gn/visual_studio_writer.cc
diff --git a/tools/gn/visual_studio_writer.cc b/tools/gn/visual_studio_writer.cc
index 76ebc5620fa39db6be2c720e848b8afd5dde3625..aa01d8217a6bcee876b3291c456efe7bb886910a 100644
--- a/tools/gn/visual_studio_writer.cc
+++ b/tools/gn/visual_studio_writer.cc
@@ -37,41 +37,9 @@
 
 namespace {
 
-std::string EscapeString(const std::string& value) {
-  std::string result;
-  for (char c : value) {
-    switch (c) {
-      case '\n':
-        result += "
";
-        break;
-      case '\r':
-        result += "
";
-        break;
-      case '\t':
-        result += "	";
-        break;
-      case '"':
-        result += """;
-        break;
-      case '<':
-        result += "&lt;";
-        break;
-      case '>':
-        result += "&gt;";
-        break;
-      case '&':
-        result += "&amp;";
-        break;
-      default:
-        result += c;
-    }
-  }
-  return result;
-}
-
 struct SemicolonSeparatedWriter {
   void operator()(const std::string& value, std::ostream& out) const {
-    out << EscapeString(value) + ';';
+    out << XmlEscape(value) + ';';
   }
 };