Keep activities stopped while the lock screen is up.

Tell the activity manager when the lock screen is shown, so it
can keep itself (mostly) in sleep mode during this time, having
the foreground actvities remain in their stopped state.

Change-Id: I71c86d3298f23a98014d7ae36fd540c9df9a64e6
diff --git a/core/java/android/app/IActivityManager.java b/core/java/android/app/IActivityManager.java
index c71b186..3fc2280 100644
--- a/core/java/android/app/IActivityManager.java
+++ b/core/java/android/app/IActivityManager.java
@@ -205,7 +205,8 @@
     // Note: probably don't want to allow applications access to these.
     public void goingToSleep() throws RemoteException;
     public void wakingUp() throws RemoteException;
-    
+    public void setLockScreenShown(boolean shown) throws RemoteException;
+
     public void unhandledBack() throws RemoteException;
     public ParcelFileDescriptor openContentUri(Uri uri) throws RemoteException;
     public void setDebugApp(
@@ -588,4 +589,5 @@
     int GET_CURRENT_USER_TRANSACTION = IBinder.FIRST_CALL_TRANSACTION+144;
     int TARGET_TASK_AFFINITY_MATCHES_ACTIVITY_TRANSACTION = IBinder.FIRST_CALL_TRANSACTION+145;
     int NAVIGATE_UP_TO_TRANSACTION = IBinder.FIRST_CALL_TRANSACTION+146;
+    int SET_LOCK_SCREEN_SHOWN_TRANSACTION = IBinder.FIRST_CALL_TRANSACTION+147;
 }