Introduce SkScopedStrike

A SkScopedStrike allows drawGlyphRunAsBMPWithPathFallback
to control the scope of SkStrikeInterface objects generated
by both RemoteGlyphCache and SkStrikeCache.

* introduce onAboutToExitScope() into the SkStrikeInterface

Change-Id: I87a1e623ee9a8375f4e063290d74a466f96c9933
Reviewed-on: https://skia-review.googlesource.com/c/191293
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Herb Derby <herb@google.com>
7 files changed