[Payments] Record CanMakePayment metrics on Desktop.

components/payments/content/payment_request_state_unittest.cc

Index: components/payments/content/payment_request_state_unittest.cc
diff --git a/components/payments/content/payment_request_state_unittest.cc b/components/payments/content/payment_request_state_unittest.cc
index 61a645ab443b1c3f08ba409302a32d084b90b139..1e2dc75b74de1305ffc4eb98d10b93152769e0f3 100644
--- a/components/payments/content/payment_request_state_unittest.cc
+++ b/components/payments/content/payment_request_state_unittest.cc
@@ -55,8 +55,8 @@ class PaymentRequestStateTest : public testing::Test,
       std::vector<mojom::PaymentMethodDataPtr> method_data) {
     // The spec will be based on the |options| and |details| passed in.
     spec_ = base::MakeUnique<PaymentRequestSpec>(
-        std::move(options), std::move(details), std::move(method_data), nullptr,
-        "en-US");
+        std::move(options), std::move(details), std::move(method_data),
+        /*observer=*/nullptr, "en-US");
     state_ = base::MakeUnique<PaymentRequestState>(
         spec_.get(), this, "en-US", &test_personal_data_manager_,
         &test_payment_request_delegate_);