New metric to track usage of the new GAIA flow.

chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc

Index: chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
index 9b0ed4859ea13ffd642c41902be4c0d014ee6122..11597974db702ddf38741102761e35b5027611d7 100644
--- a/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
@@ -121,6 +121,11 @@ void RecordSAMLScrapingVerificationResultInHistogram(bool success) {
   UMA_HISTOGRAM_BOOLEAN("ChromeOS.SAML.Scraping.VerificationResult", success);
 }
 
+void RecordGAIAFlowTypeHistogram() {
+  UMA_HISTOGRAM_BOOLEAN("ChromeOS.GAIA.WebViewFlow",
+                        StartupUtils::IsWebviewSigninEnabled());
+}
+
 // The Task posted to PostTaskAndReply in StartClearingDnsCache on the IO
 // thread.
 void ClearDnsCache(IOThread* io_thread) {
@@ -420,6 +425,8 @@ void GaiaScreenHandler::HandleCompleteAuthentication(
   if (!Delegate())
     return;
 
+  RecordGAIAFlowTypeHistogram();
+
   DCHECK(!email.empty());
   DCHECK(!gaia_id.empty());
   const std::string sanitized_email = gaia::SanitizeEmail(email);
@@ -436,6 +443,8 @@ void GaiaScreenHandler::HandleCompleteAuthenticationAuthCodeOnly(
   if (!Delegate())
     return;
 
+  RecordGAIAFlowTypeHistogram();
+
   UserContext user_context;
   user_context.SetAuthFlow(UserContext::AUTH_FLOW_EASY_BOOTSTRAP);
   user_context.SetAuthCode(auth_code);
@@ -577,6 +586,7 @@ void GaiaScreenHandler::DoCompleteLogin(const std::string& gaia_id,
 
   if (using_saml && !using_saml_api_)
     RecordSAMLScrapingVerificationResultInHistogram(true);
+  RecordGAIAFlowTypeHistogram();
 
   DCHECK(!typed_email.empty());
   DCHECK(!gaia_id.empty());