Remove explicit singletonness of ArcBridgeService part 5.

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 c6a8524cd23c4b4b01334df29c8568edab886a3c..444492a2ef2a80ee11a512cabba3fbf67682a61c 100644
--- a/components/arc/test/fake_arc_bridge_service.cc
+++ b/components/arc/test/fake_arc_bridge_service.cc
@@ -6,16 +6,9 @@
 
 namespace arc {
 
-extern ArcBridgeService* g_arc_bridge_service;
-
-FakeArcBridgeService::FakeArcBridgeService() {
-  DCHECK(!g_arc_bridge_service);
-  g_arc_bridge_service = this;
-}
+FakeArcBridgeService::FakeArcBridgeService() = default;
 
 FakeArcBridgeService::~FakeArcBridgeService() {
-  DCHECK(g_arc_bridge_service == this);
-  g_arc_bridge_service = nullptr;
   SetStopped();
 }