Add SkTypeface::getVariationDesignPosition.

Allow users to query a typeface's position in variation design space.

Change-Id: Id7cae439e795b8c9586394f11359fb7fe55e1c0b
Reviewed-on: https://skia-review.googlesource.com/8861
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Ben Wagner <bungeman@google.com>
diff --git a/tests/FontMgrTest.cpp b/tests/FontMgrTest.cpp
index 50e2d5a..b6a0cc5 100644
--- a/tests/FontMgrTest.cpp
+++ b/tests/FontMgrTest.cpp
@@ -150,6 +150,12 @@
         SkTypeface::LocalizedStrings* onCreateFamilyNameIterator() const override {
             return new EmptyLocalizedStrings;
         }
+        int onGetVariationDesignPosition(
+                SkFontArguments::VariationPosition::Coordinate coordinates[],
+                int coordinateCount) const override
+        {
+            return 0;
+        }
         int onGetTableTags(SkFontTableTag tags[]) const override { return 0; }
         size_t onGetTableData(SkFontTableTag, size_t, size_t, void*) const override {
             return 0;