[Password Manager] Add experiment controlling sync credential saving behavior

components/password_manager/core/browser/password_manager.cc

Index: components/password_manager/core/browser/password_manager.cc
diff --git a/components/password_manager/core/browser/password_manager.cc b/components/password_manager/core/browser/password_manager.cc
index cf6ef7dab13cec0dd7f3bd050503b4f6f8953df5..e05dab3878ac5999bb8748d898a43b44507c6458 100644
--- a/components/password_manager/core/browser/password_manager.cc
+++ b/components/password_manager/core/browser/password_manager.cc
@@ -19,6 +19,7 @@
 #include "components/password_manager/core/browser/password_manager_driver.h"
 #include "components/password_manager/core/browser/password_manager_metrics_util.h"
 #include "components/password_manager/core/common/password_manager_pref_names.h"
+#include "components/password_manager/core/common/password_manager_switches.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 
 using autofill::PasswordForm;
@@ -53,6 +54,21 @@ void ReportMetrics(bool password_manager_enabled) {
   UMA_HISTOGRAM_BOOLEAN("PasswordManager.Enabled", password_manager_enabled);
 }
 
+bool ShouldDropSyncCredential() {
+  std::string group_name =
+      base::FieldTrialList::FindFullName("PasswordManagerDropSyncCredential");
+
+  CommandLine* command_line = CommandLine::ForCurrentProcess();
+  if (command_line->HasSwitch(switches::kEnableDropSyncCredential))
+    return true;
+
+  if (command_line->HasSwitch(switches::kDisableDropSyncCredential))
+    return false;
+
+  // Default to not saving.
+  return group_name != "Disabled";
+}
+
 }  // namespace
 
 const char PasswordManager::kOtherPossibleUsernamesExperiment[] =
@@ -218,7 +234,8 @@ void PasswordManager::ProvisionallySavePassword(const PasswordForm& form) {
 
   // Don't save credentials for the syncing account. See crbug.com/365832 for
   // background.
-  if (client_->IsSyncAccountCredential(
+  if (ShouldDropSyncCredential() &&
+      client_->IsSyncAccountCredential(
           base::UTF16ToUTF8(form.username_value), form.signon_realm)) {
     RecordFailure(SYNC_CREDENTIAL, form.origin.host(), logger.get());
     return;