Convert app_launch_index and page_index from int to StringOrdinal.

chrome/common/string_ordinal.h

Index: chrome/common/string_ordinal.h
diff --git a/chrome/common/string_ordinal.h b/chrome/common/string_ordinal.h
index abe0fe42da124d0408ace5ba171f51d568798a84..f6c956208741e280eee3034b41a241f0fc9d35db 100644
--- a/chrome/common/string_ordinal.h
+++ b/chrome/common/string_ordinal.h
@@ -29,6 +29,11 @@ class StringOrdinal {
   // Creates an invalid StringOrdinal.
   StringOrdinal();
 
+  // Creates a valid initial StringOrdinal, this is called to create the first
+  // element of StringOrdinal list (i.e. before we have any other values we can
+  // generate from).
+  static StringOrdinal CreateInitialOrdinal();
+
   bool IsValid() const;
 
   // All remaining functions can only be called if IsValid() holds.
@@ -69,4 +74,10 @@ class StringOrdinal {
   bool is_valid_;
 };
 
+// A helper class that can be used by STL containers that require sorting.
+class StringOrdinalLessThan {
+ public:
+  bool operator() (const StringOrdinal& lhs, const StringOrdinal& rhs) const;
+};
+
 #endif  // CHROME_COMMON_STRING_ORDINAL_H_