Enable Chrome trace event facility.
Enable Chrome trace event facility.

BUG=None
TEST=None

Review URL: http://codereview.appspot.com/4973072

git-svn-id: db59699583a60be9a535cd09cdc9132301867226@421 15e8cca8-e42c-11de-a347-f34a4f72eb7d

wangming28/syzygy,ericmckean/syzygy,supriyantomaftuh/syzygy,pombreda/syzygy,sebmarchand/syzygy,google/syzygy,sebmarchand/syzygy,ericmckean/syzygy,wangming28/syzygy,pombreda/syzygy,sebmarchand/syzygy,ericmckean/syzygy,google/syzygy,ericmckean/syzygy,wangming28/syzygy,supriyantomaftuh/syzygy,supriyantomaftuh/syzygy,google/syzygy,sebmarchand/syzygy,sebmarchand/syzygy,pombreda/syzygy,wangming28/syzygy,pombreda/syzygy,Eloston/syzygy,supriyantomaftuh/syzygy,google/syzygy,pombreda/syzygy,ericmckean/syzygy,Eloston/syzygy