Reduce GrGlyph's functionality

The idea here is to move the mapping of GrGlyph to atlas location into the GrAtlasManager.

The only thing left in the GrGlyph will be the PackedGlyphID and the width/height.

Bug: 1056730
Change-Id: I6f85780eddbab701100599198b70edfed0c434dc
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/279915
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Herb Derby <herb@google.com>
diff --git a/src/gpu/text/GrTextBlob.h b/src/gpu/text/GrTextBlob.h
index c9b81ec..355be0b 100644
--- a/src/gpu/text/GrTextBlob.h
+++ b/src/gpu/text/GrTextBlob.h
@@ -28,7 +28,7 @@
 
 class GrAtlasManager;
 class GrAtlasTextOp;
-struct GrGlyph;
+class GrGlyph;
 
 class SkTextBlob;
 class SkTextBlobRunIterator;