Improve wakelock debugging:

Throw NullPointerException if tag is null in PowerManager.newWakelock()
Print wakelock owner's uid and pid in dumpsys power output.

BUG: 2522675

Change-Id: I462c7f8c49f9896b2f58cef5a678ebd2c062a8f7
Signed-off-by: Mike Lockwood <lockwood@android.com>

core/java/android/os/PowerManager.java

@@ -361,6 +361,9 @@ public class PowerManager
      */
     public WakeLock newWakeLock(int flags, String tag)
     {
+        if (tag == null) {
+            throw new NullPointerException("tag is null in PowerManager.newWakeLock");
+        }
         return new WakeLock(flags, tag);
     }
 

services/java/com/android/server/PowerManagerService.java

@@ -571,6 +571,7 @@ class PowerManagerService extends IPowerManager.Stub
             binder = b;
             tag = t;
             uid = u == MY_UID ? Process.SYSTEM_UID : u;
+            pid = Binder.getCallingPid();
             if (u != MY_UID || (
                     !"KEEP_SCREEN_ON_FLAG".equals(tag)
                     && !"KeyInputQueue".equals(tag))) {
@@ -595,6 +596,7 @@ class PowerManagerService extends IPowerManager.Stub
         final IBinder binder;
         final String tag;
         final int uid;
+        final int pid;
         final int monitorType;
         boolean activated = true;
         int minState;
@@ -998,7 +1000,8 @@ class PowerManagerService extends IPowerManager.Stub
                    activated = " activated";
                 }
                 pw.println("  " + type + " '" + wl.tag + "'" + acquireCausesWakeup
-                        + activated + " (minState=" + wl.minState + ")");
+                        + activated + " (minState=" + wl.minState + ", uid=" + wl.uid
+                        + ", pid=" + wl.pid + ")");
             }
 
             pw.println();