[ dart:developer ] Add deprecation message to MAX_USER_TAGS

Follow up to https://dart-review.googlesource.com/c/sdk/+/251120/

Change-Id: Ib7fa8d1ece6d3301489f70d58793b65e0c1cfe0b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/251240
Commit-Queue: Ben Konyi <bkonyi@google.com>
Reviewed-by: Kevin Moore <kevmoo@google.com>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index d8979c8..9b8f7c1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -34,6 +34,10 @@
 
 - Deprecates `BidirectionalIterator`.
 
+### `dart:developer`
+
+- Deprecates `UserTag.MAX_USER_TAGS` in favor of `UserTag.maxUserTags`.
+
 ### Dart VM
 
 Implementation of `async`/`async*`/`sync*` is revamped in Dart VM,
diff --git a/sdk/lib/developer/profiler.dart b/sdk/lib/developer/profiler.dart
index bf6ae6b..b134de7 100644
--- a/sdk/lib/developer/profiler.dart
+++ b/sdk/lib/developer/profiler.dart
@@ -10,9 +10,9 @@
   /// The maximum number of UserTag instances that can be created by a program.
   static const maxUserTags = 64;
 
-  @deprecated
-  // TODO: We shouldn't be using SCREAMING_CAPS for constants, so this should
-  // be removed for Dart 3.0.
+  @Deprecated("Use 'maxUserTags' instead. Will be removed in Dart 3.0.")
+  // TODO(bkonyi): We shouldn't be using SCREAMING_CAPS for constants, so this
+  // should be removed for Dart 3.0.
   static const MAX_USER_TAGS = maxUserTags;
 
   external factory UserTag(String label);