This change moves sampling from SamplerThread to the profiler events processing thread and allows to configure sampling interval on Windows.

Custom tick counter is used instead of OS::Ticks as the latter has maximum presicion of 1ms while we need 100us. QueryPerformanceCounter is used to retrieve high-precision time as described in http://msdn.microsoft.com/en-us/library/ee417693(VS.85).aspx

BUG=v8:2814
R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/23271003

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16428 ce2b1a6d-e550-0410-aec6-3dcde31c8c00