Track CPU speed stepping to get more accurate CPU cost per app.

More CPU speed stepping happening with newer devices, so we need
to qualify CPU time with the CPU speed, since power consumption
varies greatly by speed. Apps that peg the CPU should get a higher
penaltly.

Also, fix for 2062930: NPE at VolumePreference.onKey()
diff --git a/services/java/com/android/server/am/ActivityManagerService.java b/services/java/com/android/server/am/ActivityManagerService.java
index 4db5239..d4f7207e 100644
--- a/services/java/com/android/server/am/ActivityManagerService.java
+++ b/services/java/com/android/server/am/ActivityManagerService.java
@@ -1572,6 +1572,7 @@
                 }
             }
             
+            long[] cpuSpeedTimes = mProcessStats.getLastCpuSpeedTimes();
             final BatteryStatsImpl bstats = mBatteryStatsService.getActiveStatistics();
             synchronized(bstats) {
                 synchronized(mPidsSelfLocked) {
@@ -1585,11 +1586,13 @@
                                 if (pr != null) {
                                     BatteryStatsImpl.Uid.Proc ps = pr.batteryStats;
                                     ps.addCpuTimeLocked(st.rel_utime, st.rel_stime);
+                                    ps.addSpeedStepTimes(cpuSpeedTimes);
                                 } else {
                                     BatteryStatsImpl.Uid.Proc ps =
                                             bstats.getProcessStatsLocked(st.name, st.pid);
                                     if (ps != null) {
                                         ps.addCpuTimeLocked(st.rel_utime, st.rel_stime);
+                                        ps.addSpeedStepTimes(cpuSpeedTimes);
                                     }
                                 }
                             }