Hide PowerManager methods that third-party apps can't use.

Change-Id: Ie4d02b2353e8091e1f038cb73eb8128dc35b12d4
diff --git a/api/21.txt b/api/21.txt
index da98a1a..02d38fb 100644
--- a/api/21.txt
+++ b/api/21.txt
@@ -18079,12 +18079,9 @@
   }
 
   public final class PowerManager {
-    method public void goToSleep(long);
     method public boolean isScreenOn();
     method public android.os.PowerManager.WakeLock newWakeLock(int, java.lang.String);
     method public void reboot(java.lang.String);
-    method public void userActivity(long, boolean);
-    method public void wakeUp(long);
     field public static final int ACQUIRE_CAUSES_WAKEUP = 268435456; // 0x10000000
     field public static final deprecated int FULL_WAKE_LOCK = 26; // 0x1a
     field public static final int ON_AFTER_RELEASE = 536870912; // 0x20000000