Fix a race condition in ReporterTest.
Fix a race condition in ReporterTest.

BUG=
R=chrisha@chromium.org

Review URL: https://codereview.appspot.com/194230043

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