Refactor ArcBridgeService detection and initialization to a separate class ArcServiceLauncher.

components/arc/test/fake_arc_bridge_service.cc

Index: components/arc/test/fake_arc_bridge_service.cc
diff --git a/components/arc/test/fake_arc_bridge_service.cc b/components/arc/test/fake_arc_bridge_service.cc
index 200d59e60876ada85febc7926f07710850f15951..6d31bb2616bd7cfb92f7f12acb40b20477424f78 100644
--- a/components/arc/test/fake_arc_bridge_service.cc
+++ b/components/arc/test/fake_arc_bridge_service.cc
@@ -13,7 +13,8 @@ FakeArcBridgeService::~FakeArcBridgeService() {
   SetStopped();
 }
 
-void FakeArcBridgeService::DetectAvailability() {
+void FakeArcBridgeService::SetDetectionResult(bool availability) {
+  SetAvailable(availability);
 }
 
 void FakeArcBridgeService::HandleStartup() {