Fix cros login regression.

r226569 caused the continueURL not properly set.

BUG=none.

Review URL: https://codereview.chromium.org/25832002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226700 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226700
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

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226701 0039d316-1c4b-4281-b951-d872f2087c98
Tighten a DEPS rule allowing content.

Review URL: https://codereview.chromium.org/25666011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@226702 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 226701
SVN changes up to revision 226702