Adding Finch and flag for Sign-in promo

components/signin/core/common/signin_switches.h

Index: components/signin/core/common/signin_switches.h
diff --git a/components/signin/core/common/signin_switches.h b/components/signin/core/common/signin_switches.h
index 1c691257f1cd07ad2732339e4b58fde58ee8c5d2..c2dd7384193a095f9dfe3b405038ecb9cd155e8e 100644
--- a/components/signin/core/common/signin_switches.h
+++ b/components/signin/core/common/signin_switches.h
@@ -16,9 +16,11 @@ namespace switches {
 // All switches in alphabetical order. The switches should be documented
 // alongside the definition of their values in the .cc file.
 extern const char kClearTokenService[];
+extern const char kDisableSigninPromo[];
 extern const char kDisableSigninScopedDeviceId[];
 extern const char kEnableAccountConsistency[];
 extern const char kEnableRefreshTokenAnnotationRequest[];
+extern const char kEnableSigninPromo[];
 extern const char kExtensionsMultiAccount[];
 
 extern const base::Feature kUsePasswordSeparatedSigninFlow;