By default purge resources that haven't been used for 64 flushes

BUG=skia:4258

Committed: https://skia.googlesource.com/skia/+/85047175508a24f43eef49359bed215a2a3bb104

R=robertphillips@google.com

Review URL: https://codereview.chromium.org/1316233003 .
1 file changed