use SkFontMetrics so we can deprecated the typedef

Bug: skia:
Change-Id: Icd40c042b0a8251bbd0b39dd3ee1a4634fff379f
Reviewed-on: https://skia-review.googlesource.com/c/170344
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
diff --git a/samplecode/SampleRegion.cpp b/samplecode/SampleRegion.cpp
index 4c5b588..a9526fa 100644
--- a/samplecode/SampleRegion.cpp
+++ b/samplecode/SampleRegion.cpp
@@ -56,7 +56,7 @@
                            const SkPaint& paint) {
     // Need a bounds for the text
     SkRect bounds;
-    SkPaint::FontMetrics fm;
+    SkFontMetrics fm;
 
     paint.getFontMetrics(&fm);
     bounds.set(x, y + fm.fTop, x + paint.measureText(text, len), y + fm.fBottom);