Currently there are two logic in Ticker, one is to try to request a
pre-allocated TickSample from CpuProfiler and then initialize it, and if the
request fails, it will initialize a local TickSample. The other is it will pass
an initialized TickSample to Profiler to log into v8.log.

This patch splits Ticker into two samplers, the first one remains in log.cc to
collect samples and pass to Profiler for logging, the second one will be called
by ProfilerEventsProcessor, and only use the circular queue only.

BUG=v8:4789
LOG=N

Review-Url: https://codereview.chromium.org/2108393002
Cr-Commit-Position: refs/heads/master@{#37506}