More graceful shutdown for ArcSession.

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 93f0767d9d8397f5c72ab728a43512e0331956fa..d6245c688f39eed32c24f07f5e3dc43f378aa9ab 100644
--- a/components/arc/arc_bridge_service.h
+++ b/components/arc/arc_bridge_service.h
@@ -103,11 +103,18 @@ class ArcBridgeService {
   // HandleStartup() should be called upon profile startup.  This will only
   // launch an instance if the instance is enabled.
   // This can only be called on the thread that this class was created on.
-  virtual void HandleStartup() = 0;
 
-  // Shutdown() should be called when the browser is shutting down. This can
-  // only be called on the thread that this class was created on.
-  virtual void Shutdown() = 0;
+  // Starts the ARC service, then it will connect the Mojo channel. When the
+  // bridge becomes ready, OnBridgeReady() is called.
+  virtual void RequestStart() = 0;
+
+  // Stops the ARC service.
+  virtual void RequestStop() = 0;
+
+  // OnShutdown() should be called when the browser is shutting down. This can
+  // only be called on the thread that this class was created on. We assume that
+  // when this function is called, MessageLoop is no longer exists.
+  virtual void OnShutdown() = 0;

[Luis Héctor Chávez, 2016/10/21 00:43:41]

Can you add a simple unit test that uses this? I'd like to exercise the DCHECK
on the destructor a bit more.

[hidehiko, 2016/10/21 04:34:03]

Added. But which DCHECK did you mean?

If the one in ArcSession, unfortunately current we have no good way to test it.
We need more refactoring for testing. I'm happy to do that, if it looks good to
you, but let me work on it in a separate CL considering the change size.

[Luis Héctor Chávez, 2016/10/21 06:34:20]

The current unit test here looks good enough for the purpose of this change. If
there is a way to add better testing in a different change, I'm all up for it.

 
   // Adds or removes observers. This can only be called on the thread that this
   // class was created on. RemoveObserver does nothing if |observer| is not in
@@ -244,7 +251,7 @@ class ArcBridgeService {
   friend class ArcBridgeTest;
   FRIEND_TEST_ALL_PREFIXES(ArcBridgeTest, Basic);
   FRIEND_TEST_ALL_PREFIXES(ArcBridgeTest, Prerequisites);
-  FRIEND_TEST_ALL_PREFIXES(ArcBridgeTest, ShutdownMidStartup);
+  FRIEND_TEST_ALL_PREFIXES(ArcBridgeTest, StopMidStartup);
   FRIEND_TEST_ALL_PREFIXES(ArcBridgeTest, Restart);
   FRIEND_TEST_ALL_PREFIXES(ArcBridgeTest, OnBridgeStopped);