mash: Run pre-unlock animation via SessionController

ash/common/session/session_state_observer.h

Index: ash/common/session/session_state_observer.h
diff --git a/ash/common/session/session_state_observer.h b/ash/common/session/session_state_observer.h
index 5f2d344686f89b51070d4c700f116daf68778007..62bf3d7908b049a11d1578fb50dc64eda59949a7 100644
--- a/ash/common/session/session_state_observer.h
+++ b/ash/common/session/session_state_observer.h
@@ -32,6 +32,9 @@ class ASH_EXPORT SessionStateObserver {
   // Called when the login status is changed. |login_status| is the new status.
   virtual void LoginStatusChanged(LoginStatus login_status) {}
 
+  // Called when the lock state is changed. |locked| is the current lock stated.
+  virtual void OnLockStateChanged(bool locked) {}

[James Cook, 2017/04/07 20:26:55]

nit: Can this be LockStateChanged() to match the others? Or maybe the others
should be renamed to On*Changed (in a separate CL)?

[xiyuan, 2017/04/07 21:50:01]

Changed to LockStateChanged().

I will do the rename to On*Changed in a separate CL.

+
  protected:
   virtual ~SessionStateObserver() {}
 };