fonts: Cap the max number of entries in server side glyph cache tracking

The SkStrikeServer maintains a map of SkGlyphCacheState to track the
cache for a strike on the client. This entry is evicted only on a
failure to lock, which means that the map can potentially grow unbounded
if entries are not reused after eviction.

Make sure we check that they are deleted after some limit.

R=herb@google.com

Bug:878966
Change-Id: I4adb06c35661049328f6e0bde52fb1c774d0c29b
Reviewed-on: https://skia-review.googlesource.com/150443
Reviewed-by: Herb Derby <herb@google.com>
Commit-Queue: Khusal Sagar <khushalsagar@chromium.org>
3 files changed