diff --git a/services/java/com/android/server/ProcessStats.java b/services/java/com/android/server/ProcessStats.java
index 55adabb..58f8980 100644
--- a/services/java/com/android/server/ProcessStats.java
+++ b/services/java/com/android/server/ProcessStats.java
@@ -54,7 +54,10 @@
         PROC_SPACE_TERM|PROC_OUT_LONG                   // 14: stime
     };
 
+    /** Stores user time and system time in 100ths of a second. */
     private final long[] mProcessStatsData = new long[2];
+    /** Stores user time and system time in 100ths of a second. */
+    private final long[] mSinglePidStatsData = new long[2];
 
     private static final int[] PROCESS_FULL_STATS_FORMAT = new int[] {
         PROC_SPACE_TERM,
@@ -418,7 +421,18 @@
         
         return pids;
     }
-    
+
+    public long getCpuTimeForPid(int pid) {
+        final String statFile = "/proc/" + pid + "/stat";
+        final long[] statsData = mSinglePidStatsData;
+        if (Process.readProcFile(statFile, PROCESS_STATS_FORMAT,
+                null, statsData, null)) {
+            long time = statsData[0] + statsData[1];
+            return time;
+        }
+        return 0;
+    }
+
     final public int getLastUserTime() {
         return mRelUserTime;
     }
diff --git a/services/java/com/android/server/am/ActivityManagerService.java b/services/java/com/android/server/am/ActivityManagerService.java
index 3b26cb7..9650790 100644
--- a/services/java/com/android/server/am/ActivityManagerService.java
+++ b/services/java/com/android/server/am/ActivityManagerService.java
@@ -62,6 +62,7 @@
 import android.content.res.Configuration;
 import android.graphics.Bitmap;
 import android.net.Uri;
+import android.os.BatteryStats;
 import android.os.Binder;
 import android.os.Bundle;
 import android.os.Environment;
@@ -1438,7 +1439,7 @@
         synchronized (mProcessStatsThread) {
             final long now = SystemClock.uptimeMillis();
             boolean haveNewCpuStats = false;
-            
+
             if (MONITOR_CPU_USAGE &&
                     mLastCpuTime < (now-MONITOR_CPU_MIN_TIME)) {
                 mLastCpuTime = now;
@@ -2063,6 +2064,25 @@
         if (prev != null) {
             prev.resumeKeyDispatchingLocked();
         }
+
+        if (prev.app != null && prev.cpuTimeAtResume > 0 && mBatteryStatsService.isOnBattery()) {
+            long diff = 0;
+            synchronized (mProcessStatsThread) {
+                diff = mProcessStats.getCpuTimeForPid(prev.app.pid) - prev.cpuTimeAtResume;
+            }
+            if (diff > 0) {
+                BatteryStatsImpl bsi = mBatteryStatsService.getActiveStatistics();
+                synchronized (bsi) {
+                    BatteryStatsImpl.Uid.Proc ps =
+                            bsi.getProcessStatsLocked(prev.info.applicationInfo.uid,
+                            prev.info.packageName);
+                    if (ps != null) {
+                        ps.addForegroundTimeLocked(diff);
+                    }
+                }
+            }
+        }
+        prev.cpuTimeAtResume = 0; // reset it
     }
 
     /**
@@ -2095,6 +2115,17 @@
         next.resumeKeyDispatchingLocked();
         ensureActivitiesVisibleLocked(null, 0);
         mWindowManager.executeAppTransition();
+
+        // Mark the point when the activity is resuming
+        // TODO: To be more accurate, the mark should be before the onCreate,
+        //       not after the onResume. But for subsequent starts, onResume is fine.
+        if (next.app != null) {
+            synchronized (mProcessStatsThread) {
+                next.cpuTimeAtResume = mProcessStats.getCpuTimeForPid(next.app.pid);
+            }
+        } else {
+            next.cpuTimeAtResume = 0; // Couldn't get the cpu time of process
+        }
     }
 
     /**
diff --git a/services/java/com/android/server/am/HistoryRecord.java b/services/java/com/android/server/am/HistoryRecord.java
index 1789687..944ea02 100644
--- a/services/java/com/android/server/am/HistoryRecord.java
+++ b/services/java/com/android/server/am/HistoryRecord.java
@@ -66,6 +66,7 @@
     int theme;              // resource identifier of activity's theme.
     TaskRecord task;        // the task this is in.
     long startTime;         // when we starting launching this activity
+    long cpuTimeAtResume;   // the cpu time of host process at the time of resuming activity
     Configuration configuration; // configuration activity was last running in
     HistoryRecord resultTo; // who started this entry, so will get our reply
     final String resultWho; // additional identifier for use by resultTo.