libwebp: update to 0.4.1

third_party/libwebp/utils/quant_levels_dec.h

Index: third_party/libwebp/utils/quant_levels_dec.h
diff --git a/third_party/libwebp/utils/quant_levels_dec.h b/third_party/libwebp/utils/quant_levels_dec.h
index 0288383aeb7498f18a0ae0974a1e73035e225a94..9aab06807626315359a4b47dcf927f4dcba77877 100644
--- a/third_party/libwebp/utils/quant_levels_dec.h
+++ b/third_party/libwebp/utils/quant_levels_dec.h
@@ -21,11 +21,12 @@ extern "C" {
 #endif
 
 // Apply post-processing to input 'data' of size 'width'x'height' assuming that
-// the source was quantized to a reduced number of levels. The post-processing
-// will be applied to 'num_rows' rows of 'data' starting from 'row'.
-// Returns false in case of error (data is NULL, invalid parameters, ...).
-int DequantizeLevels(uint8_t* const data, int width, int height,
-                     int row, int num_rows);
+// the source was quantized to a reduced number of levels.
+// Strength is in [0..100] and controls the amount of dithering applied.
+// Returns false in case of error (data is NULL, invalid parameters,
+// malloc failure, ...).
+int WebPDequantizeLevels(uint8_t* const data, int width, int height,
+                         int strength);
 
 #ifdef __cplusplus
 }    // extern "C"