Linux: allow using GNOME Keyring and KWallet for password storage via a command line flag.

chrome/common/chrome_switches.cc

Index: chrome/common/chrome_switches.cc
===================================================================
--- chrome/common/chrome_switches.cc	(revision 50391)
+++ chrome/common/chrome_switches.cc	(working copy)
@@ -946,7 +946,12 @@
 
 // This switch is used during automated testing.
 const char kNoProcessSingletonDialog[]      = "no-process-singleton-dialog";
+
+#if !defined(OS_MACOSX)
+// Specifies which password store to use (detect, default, gnome, kwallet).
+const char kPasswordStore[]                 = "password-store";
 #endif
+#endif
 
 #if defined(OS_MACOSX)
 // Cause the OS X sandbox write to syslog every time an access to a resource