Convert app_launch_index and page_index from int to StringOrdinal.

chrome/common/extensions/extension_constants.h

Index: chrome/common/extensions/extension_constants.h
diff --git a/chrome/common/extensions/extension_constants.h b/chrome/common/extensions/extension_constants.h
index 3fbe511e65ee5675d9b4e9d9eb2e1586b12a9d84..cf99fcc0a882e26be1ddc849e435e8965301de54 100644
--- a/chrome/common/extensions/extension_constants.h
+++ b/chrome/common/extensions/extension_constants.h
@@ -344,6 +344,10 @@ namespace extension_misc {
   // The extension id of the Cloud Print component application.
   extern const char* kCloudPrintAppId;
 
+  // The string used to specify an unset app_launch_index or
+  // page index value.
+  extern const char* kUnsetIndex;
+
   // Note: this structure is an ASN.1 which encodes the algorithm used
   // with its parameters. This is defined in PKCS #1 v2.1 (RFC 3447).
   // It is encoding: { OID sha1WithRSAEncryption      PARAMETERS NULL }