Fix ArcBridgeBootstrap race issues.

components/arc/arc_bridge_service.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_ARC_ARC_BRIDGE_SERVICE_H_
 #define COMPONENTS_ARC_ARC_BRIDGE_SERVICE_H_
 
+#include <iosfwd>
 #include <string>
 #include <vector>
 
 #include "base/files/scoped_file.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "base/values.h"
 #include "components/arc/common/arc_bridge.mojom.h"
 #include "components/arc/instance_holder.h"
@@ skipping 209 matching lines @@
 
   // The reason the bridge is stopped.
   StopReason stop_reason_;
 
   // WeakPtrFactory to use callbacks.
   base::WeakPtrFactory<ArcBridgeService> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ArcBridgeService);
 };
 
+// Defines "<<" operator for LOGging purpose.
+std::ostream& operator<<(
+    std::ostream& os, ArcBridgeService::StopReason reason);
+
 }  // namespace arc
 
 #endif  // COMPONENTS_ARC_ARC_BRIDGE_SERVICE_H_