Add instrumentation for password autofill and Credential Manager API user flows.

components/password_manager/content/browser/credential_manager_impl.cc

Index: components/password_manager/content/browser/credential_manager_impl.cc
diff --git a/components/password_manager/content/browser/credential_manager_impl.cc b/components/password_manager/content/browser/credential_manager_impl.cc
index ba0cf7dda227d84da9820bc3aaca0a94be96ac08..946a3f85dc94967b91463b510bfa6e5e89b47dc6 100644
--- a/components/password_manager/content/browser/credential_manager_impl.cc
+++ b/components/password_manager/content/browser/credential_manager_impl.cc
@@ -7,6 +7,7 @@
 #include <utility>
 
 #include "base/bind.h"
+#include "base/metrics/user_metrics.h"
 #include "base/strings/string16.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/autofill/core/common/password_form.h"
@@ -250,6 +251,9 @@ void CredentialManagerImpl::SendPasswordForm(
         store->UpdateLogin(update_form);
       }
     }
+    base::RecordAction(base::UserMetricsAction("CMAPI_AccountChooser_Click"));
+  } else {
+    base::RecordAction(base::UserMetricsAction("CMAPI_AccountChooser_Dismiss"));
   }
   SendCredential(send_callback, info);
 }