This patch fixes the following issues in LocalLog:
- reverseDump() uses a descending iterator with linear complexity
instead of a quadratic loop using get(index) on a linked list.
- reverseDump() is added to ReadOnlyLocalLog.
- synchronized section in log() is restricted to mutation of internal
list.
- formatting of the log message does not create an internal
StringBuilder.
- the instance variable mNow is removed: it was only used inside log()
as a local variable.
- remaining instance variables are qualified with final.
- the linked list is replaced by a fixed capacity array-backed queue.
Test: added unit tests
Change-Id: I1a54f0ad26dd35448d3297ea24df1fd626d20ef3
de310dba78