Revert 226701 "Implement TracingController::{Enable,Disable,Capt..."

Added test base_unittests:TraceContinuousSampling fails on main waterfall

http://build.chromium.org/p/chromium.linux/buildstatus?builder=Linux%20Clang%20%28dbg%29&number=51008

TraceEventTestFixture.TraceContinuousSampling: 
../../base/debug/trace_event_unittest.cc:1814: Failure
Value of: FindNamePhase("CCC", "P")
Actual: false
Expected: true

> Implement TracingController::{Enable,Disable,Capture}Monitoring
> 
> This CL implements TracingController::EnableMonitoring,
> TracingController::DisableMonitoring and
> TracingController::CaptureMonitoringSnapshot.
> 
> BUG=241743
> TEST=base_unittests::TraceEventTestFixture.TraceContinuousSampling,
> content_browsertests::TracingControllerTest.EnableCaptureAndDisableMonitoring
> 
> Review URL: https://codereview.chromium.org/23531042

TBR=haraken@chromium.org

Review URL: https://codereview.chromium.org/25849002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226713 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226713