[DevTools] Tracing handler keeps running even after devtools frontend has been closed.
This is happening as the tracing handler is not listening to the frontend close events.
When the front-end is closed, the tracing handler is unaware of it and it keeps collecting the data.
With the active frontend close, the tracing handler should invoke DisableRecording to stop processing further.
Review URL: https://codereview.chromium.org/
337213005
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@278681 0039d316-1c4b-4281-b951-d872f2087c98