libwebp: update snapshot to v0.3.0-rc6

third_party/libwebp/enc/config.c

 // Copyright 2011 Google Inc. All Rights Reserved.
 //
 // This code is licensed under the same terms as WebM:
 //  Software License Agreement:  http://www.webmproject.org/license/software/
 //  Additional IP Rights Grant:  http://www.webmproject.org/license/additional/
 // -----------------------------------------------------------------------------
 //
 // Coding tools configuration
 //
 // Author: Skal (pascal.massimino@gmail.com)
@@ skipping 13 matching lines @@
   if (WEBP_ABI_IS_INCOMPATIBLE(version, WEBP_ENCODER_ABI_VERSION)) {
     return 0;   // caller/system version mismatch!
   }
   if (config == NULL) return 0;
 
   config->quality = quality;
   config->target_size = 0;
   config->target_PSNR = 0.;
   config->method = 4;
   config->sns_strength = 50;
-  config->filter_strength = 20;   // default: light filtering
+  config->filter_strength = 60;   // rather high filtering, helps w/ gradients.
   config->filter_sharpness = 0;
-  config->filter_type = 0;        // default: simple
+  config->filter_type = 1;        // default: strong (so U/V is filtered too)
   config->partitions = 0;
   config->segments = 4;
   config->pass = 1;
   config->show_compressed = 0;
   config->preprocessing = 0;
   config->autofilter = 0;
   config->partition_limit = 0;
   config->alpha_compression = 1;
   config->alpha_filtering = 1;
   config->alpha_quality = 100;
   config->lossless = 0;
   config->image_hint = WEBP_HINT_DEFAULT;
+  config->emulate_jpeg_size = 0;
+  config->thread_level = 0;
+  config->low_memory = 0;
 
   // TODO(skal): tune.
   switch (preset) {
     case WEBP_PRESET_PICTURE:
       config->sns_strength = 80;
       config->filter_sharpness = 4;
       config->filter_strength = 35;
       break;
     case WEBP_PRESET_PHOTO:
       config->sns_strength = 80;
@@ skipping 56 matching lines @@
   if (config->alpha_compression < 0)
     return 0;
   if (config->alpha_filtering < 0)
     return 0;
   if (config->alpha_quality < 0 || config->alpha_quality > 100)
     return 0;
   if (config->lossless < 0 || config->lossless > 1)
     return 0;
   if (config->image_hint >= WEBP_HINT_LAST)
     return 0;
+  if (config->emulate_jpeg_size < 0 || config->emulate_jpeg_size > 1)
+    return 0;
+  if (config->thread_level < 0 || config->thread_level > 1)
+    return 0;
+  if (config->low_memory < 0 || config->low_memory > 1)
+    return 0;
   return 1;
 }
 
 //------------------------------------------------------------------------------
 
 #if defined(__cplusplus) || defined(c_plusplus)
 }    // extern "C"
 #endif