Add unittests for certificate and file parsing.

net/tools/transport_security_state_generator/spki_hash.h

 // Copyright (c) 2016 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 NET_TOOLS_TRANSPORT_SECURITY_STATE_GENERATOR_SPKI_HASH_H_
 #define NET_TOOLS_TRANSPORT_SECURITY_STATE_GENERATOR_SPKI_HASH_H_
 
 #include <stdint.h>
 #include <string>
 #include <vector>
 
+#include "base/strings/string_piece.h"
+
 namespace net {
 
 namespace transport_security_state {
 
 class SPKIHash {
  public:
   enum : size_t { kLength = 32 };
 
   SPKIHash();
   ~SPKIHash();
 
   // Initalizes a hash from the form sha256/<base64-hash-value>. The preloaded
   // SPKI hashes are SHA256. Other algorithms are not supported. Returns true
   // on success and copies the decoded bytes to |data_|. Returns false on
   // failure.
-  bool FromString(const std::string& hash_string);
+  bool FromString(base::StringPiece hash_string);
 
   // Calculates the SHA256 digest over |*input| and copies the result to
   // |data_|.
   void CalculateFromBytes(const uint8_t* input, size_t input_length);
 
   // Returns the size of the hash in bytes. Harcoded to 32 which is the length
   // of a SHA256 hash.
   size_t size() const { return kLength; }
 
   uint8_t* data() { return data_; }
   const uint8_t* data() const { return data_; };
 
  private:
   // The bytes of the hash. Current hashes are SHA256 and thus 32 bytes long.
   uint8_t data_[kLength];
 };
 
 }  // namespace transport_security_state
 
 }  // namespace net
 
 #endif  // NET_TOOLS_TRANSPORT_SECURITY_STATE_GENERATOR_SPKI_HASH_H_