SkCodec: add wbmp class

src/utils/SkMD5.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkMD5_DEFINED
 #define SkMD5_DEFINED
 
@@ skipping 18 matching lines @@
         return true;
     }
 
     size_t bytesWritten() const override { return SkToSizeT(this->byteCount); }
 
     /** Processes input, adding it to the digest. Calling this after finish is undefined. */
     void update(const uint8_t* input, size_t length);
 
     struct Digest {
         uint8_t data[16];
+        bool operator ==(Digest const& other) const {
+            return 0 == memcmp(data, other.data, sizeof(data));
+        }
+        bool operator !=(Digest const& other) const {
+            return 0 != memcmp(data, other.data, sizeof(data));
+        }
     };
 
     /** Computes and returns the digest. */
     void finish(Digest& digest);
 
 private:
     // number of bytes, modulo 2^64
     uint64_t byteCount;
 
     // state (ABCD)
     uint32_t state[4];
 
     // input buffer
     uint8_t buffer[64];
 };
 
 #endif