Remove friend classes from PasswordStore.

components/password_manager/core/browser/password_store_default.cc

Index: components/password_manager/core/browser/password_store_default.cc
diff --git a/components/password_manager/core/browser/password_store_default.cc b/components/password_manager/core/browser/password_store_default.cc
index 5ee496829f3d99e93a982ebb4cdad544156b7391..8997c6f0864cb93362cf58d12b47b99f49284f8e 100644
--- a/components/password_manager/core/browser/password_store_default.cc
+++ b/components/password_manager/core/browser/password_store_default.cc
@@ -33,6 +33,7 @@ void PasswordStoreDefault::ReportMetricsImpl() {
 
 PasswordStoreChangeList PasswordStoreDefault::AddLoginImpl(
     const PasswordForm& form) {
+  DCHECK(GetBackgroundTaskRunner()->BelongsToCurrentThread());
   PasswordStoreChangeList changes;
   if (login_db_->AddLogin(form))
     changes.push_back(PasswordStoreChange(PasswordStoreChange::ADD, form));
@@ -41,6 +42,7 @@ PasswordStoreChangeList PasswordStoreDefault::AddLoginImpl(
 
 PasswordStoreChangeList PasswordStoreDefault::UpdateLoginImpl(
     const PasswordForm& form) {
+  DCHECK(GetBackgroundTaskRunner()->BelongsToCurrentThread());
   PasswordStoreChangeList changes;
   if (login_db_->UpdateLogin(form, NULL))
     changes.push_back(PasswordStoreChange(PasswordStoreChange::UPDATE, form));
@@ -49,6 +51,7 @@ PasswordStoreChangeList PasswordStoreDefault::UpdateLoginImpl(
 
 PasswordStoreChangeList PasswordStoreDefault::RemoveLoginImpl(
     const PasswordForm& form) {
+  DCHECK(GetBackgroundTaskRunner()->BelongsToCurrentThread());
   PasswordStoreChangeList changes;
   if (login_db_->RemoveLogin(form))
     changes.push_back(PasswordStoreChange(PasswordStoreChange::REMOVE, form));