Override SigninManager::SignOut if force-signin is enabled.

components/signin/core/browser/signin_manager.cc

Index: components/signin/core/browser/signin_manager.cc
diff --git a/components/signin/core/browser/signin_manager.cc b/components/signin/core/browser/signin_manager.cc
index 3880fc1f6fb4b0efd40713527a77ab2563af189d..fc3a0c503a53c9c0c5ce14b476132140f98c477a 100644
--- a/components/signin/core/browser/signin_manager.cc
+++ b/components/signin/core/browser/signin_manager.cc
@@ -125,6 +125,7 @@ void SigninManager::CopyCredentialsFrom(const SigninManager& source) {
   possibly_invalid_email_ = source.possibly_invalid_email_;
   temp_refresh_token_ = source.temp_refresh_token_;
   password_ = source.password_;
+  source.client_->AfterCredentialsCopied();
 }
 
 void SigninManager::ClearTransientSigninData() {
@@ -148,6 +149,14 @@ void SigninManager::HandleAuthError(const GoogleServiceAuthError& error) {
 void SigninManager::SignOut(
     signin_metrics::ProfileSignout signout_source_metric,
     signin_metrics::SignoutDelete signout_delete_metric) {
+  client_->PreSignOut(base::Bind(&SigninManager::DoSignOut,
+                                 base::Unretained(this), signout_source_metric,
+                                 signout_delete_metric));
+}
+
+void SigninManager::DoSignOut(
+    signin_metrics::ProfileSignout signout_source_metric,
+    signin_metrics::SignoutDelete signout_delete_metric) {
   DCHECK(IsInitialized());
 
   signin_metrics::LogSignout(signout_source_metric, signout_delete_metric);