Bug 1510853 - Make TransactionId usable for other 64bit identifiers. r=jrmuizel

MozReview-Commit-ID: 9qX9A7ZGWS8

Differential Revision: https://phabricator.services.mozilla.com/D13349

--HG--
extra : moz-landing-system : lando

gfx/layers/LayersTypes.h

@@ -79,39 +79,51 @@ struct LayersId {
   };
 };
 
-struct TransactionId {
-  uint64_t mId;
+template <typename T>
+struct BaseTransactionId {
+  uint64_t mId = 0;
 
   bool IsValid() const { return mId != 0; }
 
-  MOZ_MUST_USE TransactionId Next() const { return TransactionId{mId + 1}; }
+  MOZ_MUST_USE BaseTransactionId<T> Next() const {
+    return BaseTransactionId<T>{mId + 1};
+  }
 
-  MOZ_MUST_USE TransactionId Prev() const { return TransactionId{mId - 1}; }
+  MOZ_MUST_USE BaseTransactionId<T> Prev() const {
+    return BaseTransactionId<T>{mId - 1};
+  }
 
-  int64_t operator-(const TransactionId& aOther) const {
+  int64_t operator-(const BaseTransactionId<T>& aOther) const {
     return mId - aOther.mId;
   }
 
   // Allow explicit cast to a uint64_t for now
   explicit operator uint64_t() const { return mId; }
 
-  bool operator<(const TransactionId& aOther) const { return mId < aOther.mId; }
+  bool operator<(const BaseTransactionId<T>& aOther) const {
+    return mId < aOther.mId;
+  }
 
-  bool operator<=(const TransactionId& aOther) const {
+  bool operator<=(const BaseTransactionId<T>& aOther) const {
     return mId <= aOther.mId;
   }
 
-  bool operator>(const TransactionId& aOther) const { return mId > aOther.mId; }
+  bool operator>(const BaseTransactionId<T>& aOther) const {
+    return mId > aOther.mId;
+  }
 
-  bool operator>=(const TransactionId& aOther) const {
+  bool operator>=(const BaseTransactionId<T>& aOther) const {
     return mId >= aOther.mId;
   }
 
-  bool operator==(const TransactionId& aOther) const {
+  bool operator==(const BaseTransactionId<T>& aOther) const {
     return mId == aOther.mId;
   }
 };
 
+class TransactionIdType {};
+typedef BaseTransactionId<TransactionIdType> TransactionId;
+
 struct LayersObserverEpoch {
   uint64_t mId;
 

gfx/layers/ipc/LayersMessageUtils.h

@@ -38,9 +38,9 @@ template <>
 struct ParamTraits<mozilla::layers::LayersId>
     : public PlainOldDataSerializer<mozilla::layers::LayersId> {};
 
-template <>
-struct ParamTraits<mozilla::layers::TransactionId>
-    : public PlainOldDataSerializer<mozilla::layers::TransactionId> {};
+template <typename T>
+struct ParamTraits<mozilla::layers::BaseTransactionId<T>>
+    : public PlainOldDataSerializer<mozilla::layers::BaseTransactionId<T>> {};
 
 template <>
 struct ParamTraits<mozilla::layers::LayersObserverEpoch>