Remove unused argument in VP8LBitsEntropy.

The function is only used once and does not use the extra argument.

Change-Id: I9735383784746cb02b5a643b7a4a2037f2874bf9

src/enc/histogram_enc.c

@@ -200,14 +200,9 @@ static WEBP_INLINE double BitsEntropyRefine(const VP8LBitEntropy* entropy) {
   }
 }
 
-double VP8LBitsEntropy(const uint32_t* const array, int n,
-                       uint32_t* const trivial_symbol) {
+double VP8LBitsEntropy(const uint32_t* const array, int n) {
   VP8LBitEntropy entropy;
   VP8LBitsEntropyUnrefined(array, n, &entropy);
-  if (trivial_symbol != NULL) {
-    *trivial_symbol =
-        (entropy.nonzeros == 1) ? entropy.nonzero_code : VP8L_NON_TRIVIAL_SYM;
-  }
 
   return BitsEntropyRefine(&entropy);
 }
@@ -605,7 +600,7 @@ static void HistogramCombineEntropyBin(VP8LHistogramSet* const image_histo,
 }
 
 // Implement a Lehmer random number generator with a multiplicative constant of
-// 48271 and a modulo constant of 2^31 − 1.
+// 48271 and a modulo constant of 2^31 - 1.
 static uint32_t MyRand(uint32_t* const seed) {
   *seed = (uint32_t)(((uint64_t)(*seed) * 48271u) % 2147483647u);
   assert(*seed > 0);

src/enc/histogram_enc.h

@@ -109,10 +109,7 @@ int VP8LGetHistoImageSymbols(int xsize, int ysize,
                              uint16_t* const histogram_symbols);
 
 // Returns the entropy for the symbols in the input array.
-// Also sets trivial_symbol to the code value, if the array has only one code
-// value. Otherwise, set it to VP8L_NON_TRIVIAL_SYM.
-double VP8LBitsEntropy(const uint32_t* const array, int n,
-                       uint32_t* const trivial_symbol);
+double VP8LBitsEntropy(const uint32_t* const array, int n);
 
 // Estimate how many bits the combined entropy of literals and distance
 // approximately maps to.

src/enc/vp8l_enc.c

@@ -257,7 +257,7 @@ static int AnalyzeEntropy(const uint32_t* argb,
       ++histo[kHistoAlphaPred * 256];
 
       for (j = 0; j < kHistoTotal; ++j) {
-        entropy_comp[j] = VP8LBitsEntropy(&histo[j * 256], 256, NULL);
+        entropy_comp[j] = VP8LBitsEntropy(&histo[j * 256], 256);
       }
       entropy[kDirect] = entropy_comp[kHistoAlpha] +
           entropy_comp[kHistoRed] +