Replace --trace-gl with TRACE_DISABLED_BY_DEFAULT("cb_command")

Now TRACE_DISABLED_BY_DEFAULT() provides a better way to disable heavy
traces by default. It allows user to enable the category at runtime
in chrome://tracing.

Also changed TRACE_EVENT_BEGIN0/TRACE_EVENT_END0 to TRACE_EVENT0
which can reduce the number of events and tracing overhead by half
during tracing.

BUG=none

Review URL: https://codereview.chromium.org/29963002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230461 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230461
Output the config file in an annotated step so that it shows up on the waterfall. Might be useful to have this info right there on the waterfall/output when debugging broken bisects.

Example:

http://build.chromium.org/p/tryserver.chromium/builders/linux_perf_bisect/builds/439

BUG=306926
NOTRY=true

Review URL: https://codereview.chromium.org/35283003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230462 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230462