Implement signin using webview

components/signin/core/common/signin_switches.cc

Index: components/signin/core/common/signin_switches.cc
diff --git a/components/signin/core/common/signin_switches.cc b/components/signin/core/common/signin_switches.cc
index aa9bab1a568f3277e3577b52cccef2f4bd5f943b..c6e914ee7d47480c0523f86ceaee4494d103793e 100644
--- a/components/signin/core/common/signin_switches.cc
+++ b/components/signin/core/common/signin_switches.cc
@@ -35,6 +35,9 @@ const char kEnableNewProfileManagement[] = "new-profile-management";
 // settings page.
 const char kEnableWebBasedSignin[] = "enable-web-based-signin";
 
+// Enables the webview-based flow for sign in.
+const char kEnableWebviewBasedSignin[] = "enable-webview-based-signin";
+
 // Enables multiple account versions of chrome.identity APIs.
 const char kExtensionsMultiAccount[] = "extensions-multi-account";