Inline IMMS#doDump() into IMMS#dump()

This is a follow up CL to our previous CL [1], which extracted the
main part of IMMS#dump() into IMMS#doDump().

As of writing IMMS#doDump() is called from and only from IMMS#dump()
and those two methods are implementing a series of operations in a
sequential way.  So far there may not be any strong reason to keep
them separate.  Let's see if merging them into one method would make
more sense or not.  We can later extract out some of core logic when
necessary.

This is a mechanical refactoring without any behavior change.

This is a preparation to fix another unintentional behavior change
(Bug 177462676), which was also accidentally introduced in the same
CL.

 [1]: Ie87eb8423e2bb70f28c330983d45b95e2e07062d
      ac24994a

Bug: 154348613
Bug: 167948910
Bug: 177462676
Test: Manually done as follows.
  1. adb shell ime tracing start
  2. adb logcat -s imeTracing:*
       Make sure IME tracing started.
  3. adb shell am start -a android.intent.action.DIAL
  4. adb bugreport bugreport.zip
  5. adb logcat -s imeTracing:*
       Make sure IME tracing is stopped then restarted.
  6. unzip -v bugreport.zip | grep ime_trace_clients.pb
       Make sure "ime_trace_clients.pb" is included.
Change-Id: Icdff29885a9b4e277eea13d504d047fb3b90e7cc