Merge "DO NOT MERGE Check caller for sending media key to global priority session" into lmp-dev

import android.os.IBinder;

import android.os.Message;

import android.os.PowerManager;

import android.os.Process;

import android.os.RemoteException;

import android.os.ResultReceiver;

import android.os.ServiceManager;

            final int uid = Binder.getCallingUid();

            final long token = Binder.clearCallingIdentity();

            if (isGlobalPriorityActive() && uid != Process.SYSTEM_UID) {

                // Prevent dispatching key event through reflection while the global priority

                // session is active.

                Slog.i(TAG, "Only the system can dispatch media key event "

                        + "to the global priority session.");

                return;

            }

            try {

                synchronized (mLock) {

                    MediaSessionRecord session = mPriorityStack