Add app start source info of apps launched from launcher

Bug: 166614700
Test: Enable statsd log: "adb shell cmd stats print-logs"
      adb logcat | grep statsd | grep "(48)"
      The line may contain 0x100000->1[I] 0x110000->10[I]
      that means 1=from launcher and 10=latency 10ms.
Change-Id: Iddaff7066b66e241ba58ec87129ddbe2c531dc7e