Rename StringArray::count -> size

Convert to size to unblock removing SkTDArray::count. They are
both used as an input to a templatize function, and need to
have the size() be the same name.

Change-Id: I8380de31057b8e92f6709dfabf55fd4dacc79005
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/585742
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: John Stiles <johnstiles@google.com>
13 files changed