Enable AudioDecoder unit tests on Android

media/base/audio_hash.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_BASE_AUDIO_HASH_H_
 #define MEDIA_BASE_AUDIO_HASH_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 25 matching lines @@
  public:
   AudioHash();
   ~AudioHash();
 
   // Update current hash with the contents of the provided AudioBus.
   void Update(const AudioBus* audio_bus, int frames);
 
   // Return a string representation of the current hash.
   std::string ToString() const;
 
+  // Compare with another hash value given as string representation.

[DaleCurtis, 2016/02/26 23:31:42]

It's a bit odd having an equivalence test like this since the idea of the audio
hash is supposed to provide tolerance in the first place. That said, we get lots
of these tiny off by 1 errors, so perhaps this is nice.

+  // Returns true if for every bucket the difference between this and
+  // other is less than tolerance.
+  bool IsEquivalent(const std::string& other, double tolerance) const;
+
  private:
   // Storage for the audio hash.  The number of buckets controls the importance
   // of position in the hash.  A higher number reduces the chance of false
   // positives related to incorrect sample position.  Value chosen by dice roll.
   float audio_hash_[6];
 
   // The total number of samples processed per channel.  Uses a uint32_t instead
   // of size_t so overflows on 64-bit and 32-bit machines are equivalent.
   uint32_t sample_count_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioHash);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_HASH_H_