Fix a warning from the binder, step 2.

This patch fixes the following warning:
W/Binder: The following Binder class should be static or
  leaks might occur: android.view.inputmethod
  .InputMethodManager.ControlledInputConnectionWrapper

...in hope of removing a possible memory leaks.

Change-Id: I081d10fd839f2985d7081492f4f5cf0b4da42fd2
Bugs: 5481376, 5461066