Small fixes to battery stats.

Change-Id: Ibbf7c548a8e787a046de3659094cea64908e3deb
diff --git a/core/java/com/android/internal/os/BatteryStatsImpl.java b/core/java/com/android/internal/os/BatteryStatsImpl.java
index b73b78b..c82fef0 100644
--- a/core/java/com/android/internal/os/BatteryStatsImpl.java
+++ b/core/java/com/android/internal/os/BatteryStatsImpl.java
@@ -3631,7 +3631,9 @@
             }
             if (pid >= 0 && type == WAKE_TYPE_PARTIAL) {
                 Pid p = getPidStatsLocked(pid);
-                p.mWakeStart = SystemClock.elapsedRealtime();
+                if (p.mWakeStart == 0) {
+                    p.mWakeStart = SystemClock.elapsedRealtime();
+                }
             }
         }
 
@@ -3642,7 +3644,7 @@
             }
             if (pid >= 0 && type == WAKE_TYPE_PARTIAL) {
                 Pid p = mPids.get(pid);
-                if (p != null) {
+                if (p != null && p.mWakeStart != 0) {
                     p.mWakeSum += SystemClock.elapsedRealtime() - p.mWakeStart;
                     p.mWakeStart = 0;
                 }