OP_READ           161 net/disk_cache/blockfile/in_flight_backend_io.cc   operation_ = OP_READ;
OP_READ           292 net/disk_cache/blockfile/in_flight_backend_io.cc     case OP_READ:
OP_READ           104 net/disk_cache/tracing/tracing_cache_backend.cc                  TracingCacheBackend::OP_READ, extra, callback));
OP_READ           106 net/disk_cache/tracing/tracing_cache_backend.cc     RecordEvent(start_time, TracingCacheBackend::OP_READ, extra, rv);