Use ENABLE_DISABLE_VALUE_TYPE for storage-manager switch and enable it by default on dev.

chromeos/chromeos_switches.cc

Index: chromeos/chromeos_switches.cc
diff --git a/chromeos/chromeos_switches.cc b/chromeos/chromeos_switches.cc
index 8334b54a3b90f11721edca2a38c2e6fad2868083..a3db35c54e04eabf52f543f6d2a0e9cab5bb4137 100644
--- a/chromeos/chromeos_switches.cc
+++ b/chromeos/chromeos_switches.cc
@@ -110,6 +110,9 @@ const char kDisableOfficeEditingComponentApp[] =
 // Disables rollback option on reset screen.
 const char kDisableRollbackOption[] = "disable-rollback-option";
 
+// Disables experimental storage manager to manage local storage.
+const char kDisableStorageManager[] = "disable-storage-manager";
+
 // Disables volume adjust sound.
 const char kDisableVolumeAdjustSound[] = "disable-volume-adjust-sound";