Fix for issue 21982

pkg/analyzer/lib/instrumentation/instrumentation.dart

Index: pkg/analyzer/lib/instrumentation/instrumentation.dart
diff --git a/pkg/analyzer/lib/instrumentation/instrumentation.dart b/pkg/analyzer/lib/instrumentation/instrumentation.dart
index 3c9974c5184091083870b20bbeb0ca02f2910674..af4f6fc032b0fe8f1f808913621e1b2b43838c56 100644
--- a/pkg/analyzer/lib/instrumentation/instrumentation.dart
+++ b/pkg/analyzer/lib/instrumentation/instrumentation.dart
@@ -45,6 +45,7 @@ class InstrumentationService {
   static final InstrumentationService NULL_SERVICE =
       new InstrumentationService(null);
 
+  static const String TAG_ERROR = 'Err';
   static const String TAG_EXCEPTION = 'Ex';
   static const String TAG_NOTIFICATION = 'Noti';
   static const String TAG_REQUEST = 'Req';
@@ -69,6 +70,13 @@ class InstrumentationService {
   String get _timestamp => new DateTime.now().millisecondsSinceEpoch.toString();
 
   /**
+   * Log the fact that an error, described by the given [message], has occurred.
+   */
+  void logError(String message) {
+    _log(TAG_ERROR, message);
+  }
+
+  /**
    * Log that the given non-priority [exception] was thrown, with the given
    * [stackTrace].
    */