Update libwebp to 0.4.0

third_party/libwebp/enc/histogram.c

 // Copyright 2012 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.
 // -----------------------------------------------------------------------------
 //
 // Author: Jyrki Alakuijala (jyrki@google.com)
@@ skipping 72 matching lines @@
                                      const PixOrCopy* const v) {
   if (PixOrCopyIsLiteral(v)) {
     ++histo->alpha_[PixOrCopyLiteral(v, 3)];
     ++histo->red_[PixOrCopyLiteral(v, 2)];
     ++histo->literal_[PixOrCopyLiteral(v, 1)];
     ++histo->blue_[PixOrCopyLiteral(v, 0)];
   } else if (PixOrCopyIsCacheIdx(v)) {
     int literal_ix = 256 + NUM_LENGTH_CODES + PixOrCopyCacheIdx(v);
     ++histo->literal_[literal_ix];
   } else {
-    int code, extra_bits_count, extra_bits_value;
-    PrefixEncode(PixOrCopyLength(v),
-                 &code, &extra_bits_count, &extra_bits_value);
+    int code, extra_bits;
+    VP8LPrefixEncodeBits(PixOrCopyLength(v), &code, &extra_bits);
     ++histo->literal_[256 + code];
-    PrefixEncode(PixOrCopyDistance(v),
-                 &code, &extra_bits_count, &extra_bits_value);
+    VP8LPrefixEncodeBits(PixOrCopyDistance(v), &code, &extra_bits);
     ++histo->distance_[code];
   }
 }
 
 static double BitsEntropy(const int* const array, int n) {
   double retval = 0.;
   int sum = 0;
   int nonzeros = 0;
   int max_val = 0;
   int i;
@@ skipping 396 matching lines @@
     goto Error;
   }
   // Find the optimal map from original histograms to the final ones.
   HistogramRemap(image_out, image_in, histogram_symbols);
   ok = 1;
 
 Error:
   free(image_out);
   return ok;
 }