fix: prevent GBytes leak in GdkPixbufFromSkBitmap on Linux/GTK (#49897)

Inside gtk_util::GdkPixbufFromSkBitmap, g_bytes_new() was called
inline as an argument to gdk_pixbuf_new_from_bytes(), which per
GTK docs does not take ownership of the GBytes - it adds its own
internal reference. The caller's GBytes* was never stored or
unreffed, leaking 4 x width x height bytes of pixel data on every
call.

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: redeemer <marcin.probola@gmail.com>

shell/browser/ui/gtk_util.cc

@@ -82,11 +82,13 @@ GdkPixbuf* GdkPixbufFromSkBitmap(const SkBitmap& bitmap) {
   constexpr GdkColorspace kColorspace = GDK_COLORSPACE_RGB;
   constexpr gboolean kHasAlpha = true;
   constexpr int kBitsPerSample = 8;
-  return gdk_pixbuf_new_from_bytes(
-      g_bytes_new(std::data(bytes), std::size(bytes)), kColorspace, kHasAlpha,
-      kBitsPerSample, width, height,
+  GBytes* gbytes = g_bytes_new(std::data(bytes), std::size(bytes));
+  GdkPixbuf* pixbuf = gdk_pixbuf_new_from_bytes(
+      gbytes, kColorspace, kHasAlpha, kBitsPerSample, width, height,
       gdk_pixbuf_calculate_rowstride(kColorspace, kHasAlpha, kBitsPerSample,
                                      width, height));
+  g_bytes_unref(gbytes);
+  return pixbuf;
 }
 
 }  // namespace gtk_util