Fix kernel track hiding [again]
Fix kernel track hiding [again]

BUG=#929

Review URL: https://codereview.appspot.com/238140043

catapult-project/catapult,vmpstr/trace-viewer,catapult-project/catapult,0x90sled/catapult,zeptonaut/catapult,sahiljain/catapult,catapult-project/catapult-csm,catapult-project/catapult,SummerLW/Perf-Insight-Report,benschmaus/catapult,modulexcite/catapult,scottmcmaster/catapult,sahiljain/catapult,dstockwell/catapult,benschmaus/catapult,vmpstr/trace-viewer,dstockwell/catapult,SummerLW/Perf-Insight-Report,benschmaus/catapult,benschmaus/catapult,catapult-project/catapult-csm,dstockwell/catapult,SummerLW/Perf-Insight-Report,zeptonaut/catapult,catapult-project/catapult-csm,sahiljain/catapult,danbeam/catapult,catapult-project/catapult,SummerLW/Perf-Insight-Report,danbeam/catapult,zeptonaut/catapult,catapult-project/catapult-csm,0x90sled/catapult,SummerLW/Perf-Insight-Report,danbeam/catapult,vmpstr/trace-viewer,catapult-project/catapult,benschmaus/catapult,sahiljain/catapult,modulexcite/catapult,catapult-project/catapult-csm,benschmaus/catapult,catapult-project/catapult,scottmcmaster/catapult,catapult-project/catapult-csm,sahiljain/catapult,0x90sled/catapult,catapult-project/catapult,danbeam/catapult,SummerLW/Perf-Insight-Report,benschmaus/catapult,catapult-project/catapult-csm,scottmcmaster/catapult,sahiljain/catapult,modulexcite/catapult,dstockwell/catapult