Introduce cc::LocalFrameId and use in SurfaceFactory

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"
+
+namespace cc {
+
+class LocalFrameId {
+ public:
+  constexpr LocalFrameId() : local_id_(0), nonce_(0) {}
+
+  constexpr LocalFrameId(const LocalFrameId& other)
+      : local_id_(other.local_id_), nonce_(other.nonce_) {}
+
+  constexpr LocalFrameId(uint32_t local_id, uint64_t nonce)
+      : local_id_(local_id), nonce_(nonce) {}
+
+  constexpr bool is_null() const { return local_id_ == 0 && nonce_ == 0; }
+
+  constexpr uint32_t local_id() const { return local_id_; }
+
+  constexpr uint64_t 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_); }
+
+  std::string ToString() const {
+    return base::StringPrintf("LocalFrameId(%d, %" PRIu64 ")", local_id_,
+                              nonce_);
+  }
+
+ private:
+  uint32_t local_id_;
+  uint64_t nonce_;
+};
+
+struct LocalFrameIdHash {
+  size_t operator()(const LocalFrameId& key) const { return key.hash(); }
+};
+
+}  // namespace cc
+
+#endif  // CC_SURFACES_LOCAL_FRAME_ID_H_