Revert "Revert "SkTypeface::getAdvancedMetrics(): cleanup""

Revert "Revert "SkTypeface::getAdvancedMetrics(): cleanup""

This reverts commit 59ad782b2b05b07aa6eb961aa4d62e934093cbd1.

   - SkAdvancedTypefaceMetrics is a struct not a class
   - SkTypeface::PerGlyphInfo is gone
   - s/getAdvancedTypefaceMetrics/getAdvancedMetrics/g
   - s/onGetAdvancedTypefaceMetrics/onGetAdvancedMetrics/g
   - [on]getAdvancedMetrics now return unique_ptr rather than bare ptr.
   - [on]getAdvancedMetrics no longer has parameters. (Only caller always
     used same arguments.)
   - SkAdvancedTypefaceMetrics uses C++11 in-class member initializers.
   - SkAdvancedTypefaceMetrics no longer inherits from SkRefCnt

Change-Id: I91b56e60f7d9de7d46c426c6bd34ce124e0cf00e
Reviewed-on: https://skia-review.googlesource.com/15360
Reviewed-by: Hal Canary <halcanary@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>