TaskTree: Make use of the trivial DoneResult handlers

Change-Id: I71915fc50f073cc90b0fb2562bb82e9c4a73ccd1
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/android/androidrunnerworker.cpp

@@ -676,7 +676,7 @@ void AndroidRunnerWorker::asyncStart()
             stopOnSuccess,
             ProcessTask(onPidSetup, onPidDone, CallDoneIf::Success),
             TimeoutTask([](std::chrono::milliseconds &timeout) { timeout = 200ms; },
-                        [] { return DoneResult::Error; })
+                        DoneResult::Error)
         }.withTimeout(45s),
         ProcessTask(onUserSetup, onUserDone, CallDoneIf::Success),
         onGroupDone([pidStorage, this] { onProcessIdChanged(*pidStorage); })

src/plugins/ios/iosrunner.cpp

@@ -222,11 +222,7 @@ GroupItem DeviceCtlRunner::killProcess(Storage<AppInfo> &appInfo)
                              QString::number(appInfo->processIdentifier)}});
         return SetupResult::Continue;
     };
-    const auto onDone = [] {
-        // we tried our best and don't care at this point
-        return DoneResult::Success;
-    };
-    return ProcessTask(onSetup, onDone);
+    return ProcessTask(onSetup, DoneResult::Success); // we tried our best and don't care at this point
 }
 
 GroupItem DeviceCtlRunner::launchTask(const QString &bundleIdentifier)

tests/manual/tasking/trafficlight/recipe.cpp

@@ -21,7 +21,7 @@ Group recipe(GlueInterface *iface)
                 [iface](Barrier &barrier) {
                     QObject::connect(iface, &GlueInterface::smashed, &barrier, &Barrier::advance);
                 },
-                [] { return DoneResult::Error; }),
+                DoneResult::Error),
             Forever {
                 TimeoutTask( // "red" state
                     [iface](milliseconds &timeout) {
@@ -56,7 +56,7 @@ Group recipe(GlueInterface *iface)
                 [iface](Barrier &barrier) {
                     QObject::connect(iface, &GlueInterface::repaired, &barrier, &Barrier::advance);
                 },
-                [] { return DoneResult::Error; }),
+                DoneResult::Error),
             Forever {
                 TimeoutTask( // "blinking" state
                     [iface](milliseconds &timeout) {