Added a sleep to temporarily help with apprtc flakiness.

TBR=xians@chromium.org
BUG=303021

Review URL: https://codereview.chromium.org/35483003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230176 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230176
Reduce overhead of TRACE_MEMORY when disabled

Currently when tracing or "memory" category is not enabled, TRACE_MEMORY
will generate a funciton call. Inline the checking of 'enabled_' to
reduce the overhead.

BUG=trace-viewer:489

Review URL: https://codereview.chromium.org/32823005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230177 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230177