Convert app_launch_index and page_index from int to StringOrdinal.

chrome/common/string_ordinal.cc

Index: chrome/common/string_ordinal.cc
diff --git a/chrome/common/string_ordinal.cc b/chrome/common/string_ordinal.cc
index f07002639174353624db6cb6d9de3f82592720b1..cf1921f67c82e7514cd8e63d8ee1203c137c772f 100644
--- a/chrome/common/string_ordinal.cc
+++ b/chrome/common/string_ordinal.cc
@@ -174,6 +174,10 @@ StringOrdinal::StringOrdinal() : string_ordinal_(""),
                                  is_valid_(false) {
 }
 
+StringOrdinal StringOrdinal::CreateInitialOrdinal() {
+  return StringOrdinal(std::string(1, kMidDigit));
+}
+
 bool StringOrdinal::IsValid() const {
   return is_valid_;
 }
@@ -238,3 +242,8 @@ std::string StringOrdinal::ToString() const {
   CHECK(IsValid());
   return string_ordinal_;
 }
+
+bool StringOrdinalLessThan::operator() (const StringOrdinal& lhs,
+                                        const StringOrdinal& rhs) const {
+  return lhs.LessThan(rhs);
+}