Eagerly update the unichar to glyphID mapping.

src/core/SkGlyphCache.cpp

Index: src/core/SkGlyphCache.cpp
diff --git a/src/core/SkGlyphCache.cpp b/src/core/SkGlyphCache.cpp
index 6d978a6b5fd2d53302b9724693e9b48868c6b7c8..40d599717d0423031680f760b123c8f89ef100f4 100644
--- a/src/core/SkGlyphCache.cpp
+++ b/src/core/SkGlyphCache.cpp
@@ -91,12 +91,17 @@ SkGlyphCache::CharGlyphRec* SkGlyphCache::getCharGlyphRec(PackedUnicharID packed
 uint16_t SkGlyphCache::unicharToGlyph(SkUnichar charCode) {
     VALIDATE();
     PackedUnicharID packedUnicharID = SkGlyph::MakeID(charCode);
-    const CharGlyphRec& rec = *this->getCharGlyphRec(packedUnicharID);
+    CharGlyphRec* rec = this->getCharGlyphRec(packedUnicharID);
 
-    if (rec.fPackedUnicharID == packedUnicharID) {
-        return SkGlyph::ID2Code(rec.fPackedGlyphID);
+    if (rec->fPackedUnicharID == packedUnicharID) {
+        // The glyph exists in the unichar to glyph mapping cache. Return it.
+        return SkGlyph::ID2Code(rec->fPackedGlyphID);
     } else {
-        return fScalerContext->charToGlyphID(charCode);
+        // The glyph is not in the unichar to glyph mapping cache. Insert it.
+        rec->fPackedUnicharID = packedUnicharID;
+        uint16_t glyphID = fScalerContext->charToGlyphID(charCode);
+        rec->fPackedGlyphID = SkGlyph::MakeID(glyphID);
+        return glyphID;
     }
 }