Update libwebp to 0.4.0

third_party/libwebp/dec/quant.c

 // Copyright 2010 Google Inc. All Rights Reserved.
 //
 // Use of this source code is governed by a BSD-style license
 // that can be found in the COPYING file in the root of the source
 // tree. An additional intellectual property rights grant can be found
 // in the file PATENTS. All contributing project authors may
 // be found in the AUTHORS file in the root of the source tree.
 // -----------------------------------------------------------------------------
 //
 // Quantizer initialization
 //
 // Author: Skal (pascal.massimino@gmail.com)
 
 #include "./vp8i.h"
 
-#if defined(__cplusplus) || defined(c_plusplus)
-extern "C" {
-#endif
-
 static WEBP_INLINE int clip(int v, int M) {
   return v < 0 ? 0 : v > M ? M : v;
 }
 
 // Paragraph 14.1
 static const uint8_t kDcTable[128] = {
   4,     5,   6,   7,   8,   9,  10,  10,
   11,   12,  13,  14,  15,  16,  17,  17,
   18,   19,  20,  20,  21,  21,  22,  22,
   23,   23,  24,  25,  25,  26,  27,  28,
@@ skipping 67 matching lines @@
 
       m->y2_mat_[0] = kDcTable[clip(q + dqy2_dc, 127)] * 2;
       // For all x in [0..284], x*155/100 is bitwise equal to (x*101581) >> 16.
       // The smallest precision for that is '(x*6349) >> 12' but 16 is a good
       // word size.
       m->y2_mat_[1] = (kAcTable[clip(q + dqy2_ac, 127)] * 101581) >> 16;
       if (m->y2_mat_[1] < 8) m->y2_mat_[1] = 8;
 
       m->uv_mat_[0] = kDcTable[clip(q + dquv_dc, 117)];
       m->uv_mat_[1] = kAcTable[clip(q + dquv_ac, 127)];
+
+      m->uv_quant_ = q + dquv_ac;   // for dithering strength evaluation
     }
   }
 }
 
 //------------------------------------------------------------------------------
 
-#if defined(__cplusplus) || defined(c_plusplus)
-}    // extern "C"
-#endif