FlameChart: move CPUProfiler related part of the FlameChart into a separate file.

FlameChart was renamed to CPUProfileFlameChart
FlameChart.MainPane was renamed to FlameChart.

BUG=
R=pfeldman@chromium.org

Review URL: https://codereview.chromium.org/212593009

git-svn-id: svn://svn.chromium.org/blink/trunk@170173 bbb929c8-8fbe-4397-9dbb-9b2b20218538