Add a global setting for "Auto sign-in".

components/password_manager/content/browser/credential_manager_dispatcher.h

Index: components/password_manager/content/browser/credential_manager_dispatcher.h
diff --git a/components/password_manager/content/browser/credential_manager_dispatcher.h b/components/password_manager/content/browser/credential_manager_dispatcher.h
index 813fa9814204a3b0345d0c902bff2c6372a61e23..e5984ba2987bc036dd056145ca1092113378272b 100644
--- a/components/password_manager/content/browser/credential_manager_dispatcher.h
+++ b/components/password_manager/content/browser/credential_manager_dispatcher.h
@@ -9,6 +9,7 @@
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
+#include "base/prefs/pref_member.h"
 #include "components/password_manager/core/browser/password_store_consumer.h"
 #include "content/public/browser/web_contents_observer.h"
 
@@ -86,6 +87,9 @@ class CredentialManagerDispatcher : public content::WebContentsObserver,
   PasswordManagerClient* client_;
   scoped_ptr<CredentialManagerPasswordFormManager> form_manager_;
 
+  // Set to false to disable automatic signing in.
+  BooleanPrefMember auto_signin_enabled_;
+
   // When 'OnRequestCredential' is called, it in turn calls out to the
   // PasswordStore; we store request details here in order to properly
   // respond to the request once the PasswordStore gives us data.