Track empty username and password in PasswordStore.

components/password_manager/core/browser/login_database.cc

Index: components/password_manager/core/browser/login_database.cc
diff --git a/components/password_manager/core/browser/login_database.cc b/components/password_manager/core/browser/login_database.cc
index 4fbd3b2279808b2830ce08fe2a25c987f7337697..5d221bce14e7e27a282d562b3ecae13d25729a9f 100644
--- a/components/password_manager/core/browser/login_database.cc
+++ b/components/password_manager/core/browser/login_database.cc
@@ -8,6 +8,7 @@
 #include <limits>
 
 #include "base/bind.h"
+#include "base/debug/dump_without_crashing.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
@@ -109,6 +110,12 @@ void AddCallback(int err, sql::Statement* /*stmt*/) {
     DLOG(WARNING) << "LoginDatabase::AddLogin updated an existing form";
 }
 
+// http://crbug.com/404012. Let's see where the empty fields come from.
+void CheckForEmptyUsernameAndPassword(const PasswordForm& form) {
+  if (form.username_value.empty() && form.password_value.empty())
+    base::debug::DumpWithoutCrashing();
+}
+
 }  // namespace
 
 LoginDatabase::LoginDatabase() {
@@ -331,6 +338,7 @@ void LoginDatabase::ReportMetrics(const std::string& sync_username) {
 }
 
 PasswordStoreChangeList LoginDatabase::AddLogin(const PasswordForm& form) {
+  CheckForEmptyUsernameAndPassword(form);
   PasswordStoreChangeList list;
   std::string encrypted_password;
   if (EncryptedString(form.password_value, &encrypted_password) !=
@@ -372,6 +380,7 @@ PasswordStoreChangeList LoginDatabase::AddLogin(const PasswordForm& form) {
 }
 
 PasswordStoreChangeList LoginDatabase::UpdateLogin(const PasswordForm& form) {
+  CheckForEmptyUsernameAndPassword(form);
   std::string encrypted_password;
   if (EncryptedString(form.password_value, &encrypted_password) !=
           ENCRYPTION_RESULT_SUCCESS)