GH-1053 explode launch task into many small steps, each a Task

logic/launch/steps/ModMinecraftJar.cpp

@@ -0,0 +1,44 @@
+/* Copyright 2013-2015 MultiMC Contributors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "ModMinecraftJar.h"
+#include <launch/LaunchTask.h>
+#include <QStandardPaths>
+
+void ModMinecraftJar::executeTask()
+{
+	m_jarModTask = m_parent->instance()->createJarModdingTask();
+	if(m_jarModTask)
+	{
+		connect(m_jarModTask.get(), SIGNAL(finished()), this, SLOT(jarModdingFinished()));
+		m_jarModTask->start();
+		return;
+	}
+	emitSucceeded();
+}
+
+void ModMinecraftJar::jarModdingFinished()
+{
+	if(m_jarModTask->successful())
+	{
+		emitSucceeded();
+	}
+	else
+	{
+		QString reason = tr("jar modding failed because: %1.\n\n").arg(m_jarModTask->failReason());
+		emit logLine(reason, MessageLevel::Fatal);
+		emitFailed(reason);
+	}
+}