arc: Notify ARC instance failures via callbacks.

components/arc/arc_bridge_service.h

Index: components/arc/arc_bridge_service.h
diff --git a/components/arc/arc_bridge_service.h b/components/arc/arc_bridge_service.h
index 3d719694314ee0219463b873144255e23136cbde..0dd1fd44c64680716c5940a28d0b40ffae752a1d 100644
--- a/components/arc/arc_bridge_service.h
+++ b/components/arc/arc_bridge_service.h
@@ -21,8 +21,6 @@ class CommandLine;
 
 namespace arc {
 
-class ArcBridgeBootstrap;
-
 // The Chrome-side service that handles ARC instances and ARC bridge creation.
 // This service handles the lifetime of ARC instances and sets up the
 // communication channel (the ARC bridge) used to send and receive messages.
@@ -63,13 +61,34 @@ class ArcBridgeService : public mojom::ArcBridgeHost {
     STOPPING,
   };
 
+  // Describes the reason the bridge is being aborted.
+  enum class AbortReason {
+    // ARC instance boot failed for unknown errors.

[Luis Héctor Chávez, 2016/07/08 18:01:02]

nit: it's better to say that this is just any error that happens during the
setup before the instance is actually attempted to be started.

[Shuhei Takahashi, 2016/07/11 08:25:19]

Thanks, I've updated the comment. Does it look good to you?

[Luis Héctor Chávez, 2016/07/11 22:28:50]

It does, thanks!

+    GENERIC_BOOT_FAILURE,
+
+    // ARC instance has crashed.
+    CRASH,
+  };
+
   // Notifies life cycle events of ArcBridgeService.
   class Observer {
    public:
     // Called whenever the state of the bridge has changed.
     // TODO(lchavez): Rename to OnStateChangedForTest
     virtual void OnStateChanged(State state) {}
+
+    // Called whenever the bridge got ready.

[Luis Héctor Chávez, 2016/07/08 18:01:02]

nit: the bridge is ready.

[Shuhei Takahashi, 2016/07/11 08:25:19]

Done.

     virtual void OnBridgeReady() {}
+
+    // Called whenever the bridge is being aborted due to errors.
+    // After this callback is invoked, the ARC instance will be stopped, so
+    // you do not need to call ArcBridgeServiceImpl::StopInstance() in the
+    // callback.
+    virtual void OnBridgeAborting(AbortReason reason) {}
+
+    // Called whenever the bridge stopped.

[Luis Héctor Chávez, 2016/07/08 18:01:02]

nit: the bridge is stopped.

[Shuhei Takahashi, 2016/07/11 08:25:19]

Done.

+    // When the bridge aborted due to errors, OnBridgeAborting() is called
+    // first, then OnBridgeStopped() is called once the instance is stopped.
     virtual void OnBridgeStopped() {}
 
     // Called whenever ARC's availability has changed for this system.