[Password Manager] Add experiment controlling sync credential saving behavior

components/password_manager/core/common/password_manager_switches.cc

Index: components/password_manager/core/common/password_manager_switches.cc
diff --git a/components/password_manager/core/common/password_manager_switches.cc b/components/password_manager/core/common/password_manager_switches.cc
index 31cba89fb6aebe812380283270be1261c8392e5f..25d75f01e210aa3b7f8c834a2c4d353063fb884f 100644
--- a/components/password_manager/core/common/password_manager_switches.cc
+++ b/components/password_manager/core/common/password_manager_switches.cc
@@ -8,10 +8,18 @@ namespace password_manager {
 
 namespace switches {
 
+// Disable dropping the credential used to sync passwords.
+const char kDisableDropSyncCredential[] =
+    "disable-drop-sync-credential";
+
 // Disable both saving and filling for the sync signin form.
 const char kDisableManagerForSyncSignin[] =
     "disable-manager-for-sync-signin";
 
+// Enable dropping the credential used to sync passwords.
+const char kEnableDropSyncCredential[] =
+    "enable-drop-sync-credential";
+
 // Enable saving and filling for the sync signin form. Currently the default
 // behavior.
 const char kEnableManagerForSyncSignin[] =