Triggering logging on rematched typeface

render_text_harfbuzz_patch.diff

--- a/ui/gfx/render_text_harfbuzz.cc
+++ b/ui/gfx/render_text_harfbuzz.cc
@@ -796,11 +796,33 @@ bool TextRunHarfBuzz::FontParams::SetRenderParamsRematchFont(
   // scenarios, as the fallback font may be of a different weight and style than
   // the run's own, so this can lead to a failure of instantiating the correct
   // fallback font.
+
+  sk_sp<SkTypeface> before_rematch;
+  PlatformFont* platform_font = new_font.platform_font();
+  if (platform_font) {
+    before_rematch = platform_font->GetNativeSkTypefaceIfAvailable();
+  }
+
   sk_sp<SkTypeface> new_skia_face(
       internal::CreateSkiaTypeface(new_font, italic, weight));
   if (!new_skia_face)
     return false;

+  if (before_rematch->fontStyle().weight() != new_skia_face->fontStyle().weight() ||
+      before_rematch->fontStyle().slant() != new_skia_face->fontStyle().slant()) {
+    SkString family_before;
+    SkString family_after;
+    before_rematch->getFamilyName(&family_before);
+    new_skia_face->getFamilyName(&family_after);
+    VLOG(4) << "rematching lead to new font style: fam before: "
+                 << family_before.c_str()
+                 << " fam after: " << family_after.c_str()
+                 << " weights: " << before_rematch->fontStyle().weight() << ":"
+                 << new_skia_face->fontStyle().weight()
+                 << " slants: " << before_rematch->fontStyle().slant() << ":"
+                 << new_skia_face->fontStyle().slant();
+  }
+
   skia_face = new_skia_face;
   font = new_font;
   render_params = new_render_params;