DevTools: enable by default disableAgentsWhenProfile experiment

profilingLock was replaced with WebInspector.targetManager.suspendAllTargets/resumeAllTargets calls and TargetManager.Events.SuspendStateChanged event. 

BUG=

Review URL: https://codereview.chromium.org/614323003

git-svn-id: svn://svn.chromium.org/blink/trunk@183942 bbb929c8-8fbe-4397-9dbb-9b2b20218538