PaymentApp: Implement PaymentAppProvider for LayoutTest.

components/test_runner/test_runner_for_specific_view.h

Index: components/test_runner/test_runner_for_specific_view.h
diff --git a/components/test_runner/test_runner_for_specific_view.h b/components/test_runner/test_runner_for_specific_view.h
index 8fb82b0aface587bf39f28a923eb7af296fbac90..c1a4468594128a5ff283a46c39851de9aad7e745 100644
--- a/components/test_runner/test_runner_for_specific_view.h
+++ b/components/test_runner/test_runner_for_specific_view.h
@@ -120,6 +120,11 @@ class TestRunnerForSpecificView {
   void SendBluetoothManualChooserEvent(const std::string& event,
                                        const std::string& argument);
 
+  void GetAllPaymentAppIDs(v8::Local<v8::Function> callback);
+  void GetAllPaymentAppIDsCallback(v8::UniquePersistent<v8::Function> callback,
+                                   const std::vector<int64_t>& ids);
+  void InvokePaymentApp(int64_t registration_id);
+
   // Used to set the device scale factor.
   void SetBackingScaleFactor(double value, v8::Local<v8::Function> callback);