move usability log code to new class (ResearchLogger) and clean api

This change also undoes the effects of I8694eb9016, which was an initial
effort built on Utils.UsabilityStudyLogs.  Now Utils operates as it did
previously, for backward compatibility, but the ResearchLogger retains
the new log format.

Coordinated with  I274b75c5.

Bug: 6188932
Change-Id: I41208bdc6b511f69a010c9fc38a936521beba7d5
4 files changed
tree: 1e789af07b6c51925439f56ff372df1629644158
  1. dictionaries/
  2. java/
  3. native/
  4. tests/
  5. tools/
  6. Android.mk
  7. CleanSpec.mk