tree 432b0fd007831594f69ad84926c8ce244a4460d2
parent defcf4e29e72c704e6aa19af8a88ab6e06735347
author Yabin Cui <yabinc@google.com> 1437622243 -0700
committer Yabin Cui <yabinc@google.com> 1437622580 -0700

Simpleperf: separate ThreadTree from SampleTree.

It is a preparation for unwinding in record command.

Bug: 22229391
Change-Id: I2f5c6df3f7332d4c98b61c7f9f922456b5bbeaaa