Remove explicit singletonness of ArcBridgeService part 1.

components/arc/arc_bridge_host_impl.h

Index: components/arc/arc_bridge_host_impl.h
diff --git a/components/arc/arc_bridge_host_impl.h b/components/arc/arc_bridge_host_impl.h
index b99a4953f2fa87d5b62d6a0a9b3888b87e64d77a..b42072583a46b74ad5465168d45af6620b7677b3 100644
--- a/components/arc/arc_bridge_host_impl.h
+++ b/components/arc/arc_bridge_host_impl.h
@@ -17,6 +17,8 @@
 
 namespace arc {
 
+class ArcBridgeService;
+
 // Implementation of the ArcBridgeHost.
 // The lifetime of ArcBridgeHost and ArcBridgeInstance mojo channels are tied
 // to this instance. Also, any ARC related Mojo channel will be closed if
@@ -31,7 +33,8 @@ class ArcBridgeHostImpl : public mojom::ArcBridgeHost {
   // Interface to keep the Mojo channel InterfacePtr.
   class MojoChannel;
 
-  explicit ArcBridgeHostImpl(mojom::ArcBridgeInstancePtr instance);
+  ArcBridgeHostImpl(ArcBridgeService* arc_bridge_service,
+                    mojom::ArcBridgeInstancePtr instance);
   ~ArcBridgeHostImpl() override;
 
   // ArcBridgeHost overrides.
@@ -86,6 +89,9 @@ class ArcBridgeHostImpl : public mojom::ArcBridgeHost {
 
   base::ThreadChecker thread_checker_;
 
+  // Owned by ArcServiceManager.
+  ArcBridgeService* const arc_bridge_service_;
+
   mojo::Binding<mojom::ArcBridgeHost> binding_;
   mojom::ArcBridgeInstancePtr instance_;