arc: Notify ARC instance failures via callbacks.

components/arc/arc_bridge_service.cc

Index: components/arc/arc_bridge_service.cc
diff --git a/components/arc/arc_bridge_service.cc b/components/arc/arc_bridge_service.cc
index 179cde95e721386b0dfb1b13311f8e9dba1766f0..22ee97e5170ed681a545100c42fe458bb2ec4f92 100644
--- a/components/arc/arc_bridge_service.cc
+++ b/components/arc/arc_bridge_service.cc
@@ -17,8 +17,10 @@ namespace arc {
 ArcBridgeService* g_arc_bridge_service = nullptr;
 
 ArcBridgeService::ArcBridgeService()
-    : available_(false), state_(State::STOPPED), weak_factory_(this) {
-}
+    : available_(false),
+      state_(State::STOPPED),
+      stop_reason_(StopReason::NO_ERROR),
+      weak_factory_(this) {}
 
 ArcBridgeService::~ArcBridgeService() {
   DCHECK(CalledOnValidThread());
@@ -584,7 +586,7 @@ void ArcBridgeService::SetState(State state) {
   if (state_ == State::READY)
     FOR_EACH_OBSERVER(Observer, observer_list(), OnBridgeReady());
   else if (state == State::STOPPED)
-    FOR_EACH_OBSERVER(Observer, observer_list(), OnBridgeStopped());
+    FOR_EACH_OBSERVER(Observer, observer_list(), OnBridgeStopped(stop_reason_));
 }
 
 void ArcBridgeService::SetAvailable(bool available) {
@@ -594,6 +596,11 @@ void ArcBridgeService::SetAvailable(bool available) {
   FOR_EACH_OBSERVER(Observer, observer_list(), OnAvailableChanged(available_));
 }
 
+void ArcBridgeService::SetStopReason(StopReason stop_reason) {
+  DCHECK(CalledOnValidThread());
+  stop_reason_ = stop_reason;
+}
+
 bool ArcBridgeService::CalledOnValidThread() {
   return thread_checker_.CalledOnValidThread();
 }