Implement new password separated sign in flow for chrome desktop.

components/signin/core/common/profile_management_switches.h

Index: components/signin/core/common/profile_management_switches.h
diff --git a/components/signin/core/common/profile_management_switches.h b/components/signin/core/common/profile_management_switches.h
index c1ad76134e6979cf4ec58b6028e51619c3ff6d4d..9b8743c5da8446dca23ea8c25cf6d810d6426625 100644
--- a/components/signin/core/common/profile_management_switches.h
+++ b/components/signin/core/common/profile_management_switches.h
@@ -39,6 +39,9 @@ bool IsNewProfileManagement();
 // Whether the new profile management preview has been enabled.
 bool IsNewProfileManagementPreviewEnabled();
 
+// Checks whether the new gaia password separated sign in flow is enabled.
+bool UseNewGaiaFlow();
+
 // Called in tests to force enabling different modes.
 void EnableNewAvatarMenuForTesting(base::CommandLine* command_line);
 void DisableNewAvatarMenuForTesting(base::CommandLine* command_line);