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

cc/surfaces/local_frame_id.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 CC_SURFACES_LOCAL_FRAME_ID_H_
 #define CC_SURFACES_LOCAL_FRAME_ID_H_
 
 #include <inttypes.h>
 #include <tuple>
 
 #include "base/hash.h"
 #include "base/strings/stringprintf.h"
+#include "base/unguessable_token.h"
 
 namespace cc {
 
 class LocalFrameId {
  public:
-  constexpr LocalFrameId() : local_id_(0), nonce_(0) {}
+  constexpr LocalFrameId() : local_id_(0) {}
 
   constexpr LocalFrameId(const LocalFrameId& other)
       : local_id_(other.local_id_), nonce_(other.nonce_) {}
 
-  constexpr LocalFrameId(uint32_t local_id, uint64_t nonce)
+  explicit LocalFrameId(uint32_t local_id)

[Fady Samuel, 2016/10/07 14:18:11]

Do we need this constructor? Can we simply create the unguessabletoken in
SurfaceIdAllocator and pass it in like we did before.

[Alex Z., 2016/10/07 14:27:49]

Done.

+      : local_id_(local_id), nonce_(base::UnguessableToken::Create()) {}
+
+  constexpr LocalFrameId(uint32_t local_id, const base::UnguessableToken& nonce)
       : local_id_(local_id), nonce_(nonce) {}
 
-  constexpr bool is_null() const { return local_id_ == 0 && nonce_ == 0; }
+  constexpr bool is_null() const { return local_id_ == 0 && nonce_.is_empty(); }
 
   constexpr uint32_t local_id() const { return local_id_; }
 
-  constexpr uint64_t nonce() const { return nonce_; }
+  constexpr const base::UnguessableToken& nonce() const { return nonce_; }
 
   bool operator==(const LocalFrameId& other) const {
     return local_id_ == other.local_id_ && nonce_ == other.nonce_;
   }
 
   bool operator!=(const LocalFrameId& other) const { return !(*this == other); }
 
   bool operator<(const LocalFrameId& other) const {
     return std::tie(local_id_, nonce_) <
            std::tie(other.local_id_, other.nonce_);
   }
 
-  size_t hash() const { return base::HashInts(local_id_, nonce_); }
+  size_t hash() const {
+    return base::HashInts(local_id_, base::UnguessableTokenHash()(nonce_));
+  }
 
   std::string ToString() const {
-    return base::StringPrintf("LocalFrameId(%d, %" PRIu64 ")", local_id_,
-                              nonce_);
+    return base::StringPrintf("LocalFrameId(%d, %s" PRIu64 ")", local_id_,
+                              nonce_.ToString().c_str());
   }
 
  private:
   uint32_t local_id_;
-  uint64_t nonce_;
+  base::UnguessableToken nonce_;
 };
 
 struct LocalFrameIdHash {
   size_t operator()(const LocalFrameId& key) const { return key.hash(); }
 };
 
 }  // namespace cc
 
 #endif  // CC_SURFACES_LOCAL_FRAME_ID_H_