Battery stats: wake locks, radio active, cleanup.

- Improve wake lock work source updates to also update the current
  history tag, in case the new work source gets recorded in the
  history.

- Fix bug in recording radio active time that was not distributing
  any time to apps.

- No longer hold a wake lock while dispatching data conn active call,
  since it comes with its own timestamp.

- Fix issue where the top app was not being cleared while the screen
  was off.

- Remove obsolete STATS_LAST stats type.

- Fix bug that was not clearing the total run time when resetting
  the stats.

Change-Id: Iabe17a9edf34f762374ae09fcffb8a819cf72e30

services/core/java/com/android/server/NativeDaemonConnector.java

@@ -110,7 +110,7 @@ final class NativeDaemonConnector implements Runnable, Handler.Callback, Watchdo
         } catch (Exception e) {
             loge("Error handling '" + event + "': " + e);
         } finally {
-            if (mCallbacks.onCheckHoldWakeLock(msg.what)) {
+            if (mCallbacks.onCheckHoldWakeLock(msg.what) && mWakeLock != null) {
                 mWakeLock.release();
             }
         }
@@ -171,7 +171,8 @@ final class NativeDaemonConnector implements Runnable, Handler.Callback, Watchdo
                                     rawEvent);
                             if (event.isClassUnsolicited()) {
                                 // TODO: migrate to sending NativeDaemonEvent instances
-                                if (mCallbacks.onCheckHoldWakeLock(event.getCode())) {
+                                if (mCallbacks.onCheckHoldWakeLock(event.getCode())
+                                        && mWakeLock != null) {
                                     mWakeLock.acquire();
                                     releaseWl = true;
                                 }