Revert "Revert "Allow GrDrawOpAtlas to grow as needed""

Bug: skia:3550
Change-Id: I11a3b39ed7470542447f0e46141a26eef7a9bdaf
Reviewed-on: https://skia-review.googlesource.com/47240
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
diff --git a/src/gpu/GrGlyph.h b/src/gpu/GrGlyph.h
index 5005b74..fbd389e 100644
--- a/src/gpu/GrGlyph.h
+++ b/src/gpu/GrGlyph.h
@@ -61,6 +61,7 @@
     int height() const { return fBounds.height(); }
     bool isEmpty() const { return fBounds.isEmpty(); }
     uint16_t glyphID() const { return UnpackID(fPackedID); }
+    uint32_t pageIndex() const { return GrDrawOpAtlas::GetPageIndexFromID(fID); }
 
     ///////////////////////////////////////////////////////////////////////////