Replaced cc::SurfaceId::nonce_ with base::UnguessableToken

base/unguessable_token.h

 // Copyright 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 BASE_UNGUESSABLE_TOKEN_H_
 #define BASE_UNGUESSABLE_TOKEN_H_
 
 #include <stdint.h>
 #include <string.h>
 #include <iosfwd>
@@ skipping 27 matching lines @@
 
   // Return a UnguessableToken built from the high/low bytes provided.
   // It should only be used in deserialization scenarios.
   //
   // NOTE: If the deserialized token is empty, it means that it was never
   // initialized via Create(). This is a security issue, and should be handled.
   static UnguessableToken Deserialize(uint64_t high, uint64_t low);
 
   // Creates an empty UnguessableToken.
   // Assign to it with Create() before using it.
-  UnguessableToken() = default;
+  constexpr UnguessableToken() = default;
 
   // NOTE: Serializing an empty UnguessableToken is an illegal operation.
   uint64_t GetHighForSerialization() const {
     DCHECK(!is_empty());
     return high_;
   };
 
   // NOTE: Serializing an empty UnguessableToken is an illegal operation.
   uint64_t GetLowForSerialization() const {
     DCHECK(!is_empty());
@@ skipping 35 matching lines @@
 struct UnguessableTokenHash {
   size_t operator()(const base::UnguessableToken& token) const {
     DCHECK(token);
     return base::HashInts64(token.high_, token.low_);
   }
 };
 
 }  // namespace base
 
 #endif  // BASE_UNGUESSABLE_TOKEN_H_