diff --git a/pkg/analysis_server/doc/api.html b/pkg/analysis_server/doc/api.html
index ab38556b71a..a3f8ce1bef0 100644
--- a/pkg/analysis_server/doc/api.html
+++ b/pkg/analysis_server/doc/api.html
@@ -3713,7 +3713,7 @@ a:focus, a:hover {
       An enumeration of the kinds of elements.
     </p>
     
-  <dl><dt class="value">CLASS</dt><dt class="value">CLASS_TYPE_ALIAS</dt><dt class="value">COMPILATION_UNIT</dt><dt class="value">CONSTRUCTOR</dt><dt class="value">CONSTRUCTOR_INVOCATION</dt><dt class="value">ENUM</dt><dt class="value">ENUM_CONSTANT</dt><dt class="value">FIELD</dt><dt class="value">FILE</dt><dt class="value">FUNCTION</dt><dt class="value">FUNCTION_INVOCATION</dt><dt class="value">FUNCTION_TYPE_ALIAS</dt><dt class="value">GETTER</dt><dt class="value">LABEL</dt><dt class="value">LIBRARY</dt><dt class="value">LOCAL_VARIABLE</dt><dt class="value">METHOD</dt><dt class="value">MIXIN</dt><dt class="value">PARAMETER</dt><dt class="value">PREFIX</dt><dt class="value">SETTER</dt><dt class="value">TOP_LEVEL_VARIABLE</dt><dt class="value">TYPE_PARAMETER</dt><dt class="value">UNIT_TEST_GROUP</dt><dt class="value">UNIT_TEST_TEST</dt><dt class="value">UNKNOWN</dt></dl></dd><dt class="typeDefinition"><a name="type_ExecutableFile">ExecutableFile: object</a></dt><dd>
+  <dl><dt class="value">CLASS</dt><dt class="value">CLASS_TYPE_ALIAS</dt><dt class="value">COMPILATION_UNIT</dt><dt class="value">CONSTRUCTOR</dt><dt class="value">CONSTRUCTOR_INVOCATION</dt><dt class="value">ENUM</dt><dt class="value">ENUM_CONSTANT</dt><dt class="value">EXTENSION</dt><dt class="value">FIELD</dt><dt class="value">FILE</dt><dt class="value">FUNCTION</dt><dt class="value">FUNCTION_INVOCATION</dt><dt class="value">FUNCTION_TYPE_ALIAS</dt><dt class="value">GETTER</dt><dt class="value">LABEL</dt><dt class="value">LIBRARY</dt><dt class="value">LOCAL_VARIABLE</dt><dt class="value">METHOD</dt><dt class="value">MIXIN</dt><dt class="value">PARAMETER</dt><dt class="value">PREFIX</dt><dt class="value">SETTER</dt><dt class="value">TOP_LEVEL_VARIABLE</dt><dt class="value">TYPE_PARAMETER</dt><dt class="value">UNIT_TEST_GROUP</dt><dt class="value">UNIT_TEST_TEST</dt><dt class="value">UNKNOWN</dt></dl></dd><dt class="typeDefinition"><a name="type_ExecutableFile">ExecutableFile: object</a></dt><dd>
     <p>
       A description of an executable file.
     </p>
diff --git a/pkg/analysis_server/lib/src/computer/computer_outline.dart b/pkg/analysis_server/lib/src/computer/computer_outline.dart
index aebb4165298..0315200e687 100644
--- a/pkg/analysis_server/lib/src/computer/computer_outline.dart
+++ b/pkg/analysis_server/lib/src/computer/computer_outline.dart
@@ -42,6 +42,9 @@ class DartUnitOutlineComputer {
           constantOutlines.add(_newEnumConstant(constant));
         }
         unitContents.add(_newEnumOutline(enumDeclaration, constantOutlines));
+      } else if (unitMember is ExtensionDeclaration) {
+        unitContents.add(_newExtensionOutline(
+            unitMember, _outlinesForMembers(unitMember.members)));
       } else if (unitMember is TopLevelVariableDeclaration) {
         TopLevelVariableDeclaration fieldDeclaration = unitMember;
         VariableDeclarationList fields = fieldDeclaration.variables;
@@ -92,7 +95,6 @@ class DartUnitOutlineComputer {
   }
 
   Outline _newClassOutline(ClassDeclaration node, List<Outline> classContents) {
-    node.firstTokenAfterCommentAndMetadata;
     SimpleIdentifier nameNode = node.name;
     String name = nameNode.name;
     Element element = new Element(
@@ -175,6 +177,21 @@ class DartUnitOutlineComputer {
     return _nodeOutline(node, element, children);
   }
 
+  Outline _newExtensionOutline(
+      ExtensionDeclaration node, List<Outline> extensionContents) {
+    SimpleIdentifier nameNode = node.name;
+    String name = nameNode?.name ?? '';
+    Element element = new Element(
+        ElementKind.EXTENSION,
+        name,
+        Element.makeFlags(
+            isPrivate: Identifier.isPrivateName(name),
+            isDeprecated: _isDeprecated(node)),
+        location: _getLocationNode(nameNode ?? node.extendedType),
+        typeParameters: _getTypeParametersStr(node.typeParameters));
+    return _nodeOutline(node, element, extensionContents);
+  }
+
   Outline _newFunctionOutline(FunctionDeclaration function, bool isStatic) {
     TypeAnnotation returnType = function.returnType;
     SimpleIdentifier nameNode = function.name;
diff --git a/pkg/analysis_server/test/integration/support/protocol_matchers.dart b/pkg/analysis_server/test/integration/support/protocol_matchers.dart
index ab3dae87e73..aa49a58e724 100644
--- a/pkg/analysis_server/test/integration/support/protocol_matchers.dart
+++ b/pkg/analysis_server/test/integration/support/protocol_matchers.dart
@@ -470,6 +470,7 @@ final Matcher isElementDeclaration =
  *   CONSTRUCTOR_INVOCATION
  *   ENUM
  *   ENUM_CONSTANT
+ *   EXTENSION
  *   FIELD
  *   FILE
  *   FUNCTION
@@ -499,6 +500,7 @@ final Matcher isElementKind = new MatchesEnum("ElementKind", [
   "CONSTRUCTOR_INVOCATION",
   "ENUM",
   "ENUM_CONSTANT",
+  "EXTENSION",
   "FIELD",
   "FILE",
   "FUNCTION",
diff --git a/pkg/analysis_server/test/src/computer/outline_computer_test.dart b/pkg/analysis_server/test/src/computer/outline_computer_test.dart
index bfd4ce53559..ac637b408c7 100644
--- a/pkg/analysis_server/test/src/computer/outline_computer_test.dart
+++ b/pkg/analysis_server/test/src/computer/outline_computer_test.dart
@@ -5,6 +5,7 @@
 import 'dart:async';
 
 import 'package:analysis_server/src/computer/computer_outline.dart';
+import 'package:analyzer/src/dart/analysis/experiments.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart';
 import 'package:meta/meta.dart';
 import 'package:test/test.dart';
@@ -413,6 +414,68 @@ enum MyEnum {
     }
   }
 
+  test_extension_named() async {
+    createAnalysisOptionsFile(experiments: [EnableString.extension_methods]);
+    Outline unitOutline = await _computeOutline('''
+extension MyExt on String {
+  int get halfLength => length ~/ 2;
+  void writeOn(StringBuffer b) {
+    b.write(this);
+  }
+}
+''');
+    List<Outline> topOutlines = unitOutline.children;
+    expect(topOutlines, hasLength(1));
+    // MyExt
+    {
+      Outline outline_MyExt = topOutlines[0];
+      Element element_MyExt = outline_MyExt.element;
+      expect(element_MyExt.kind, ElementKind.EXTENSION);
+      expect(element_MyExt.name, 'MyExt');
+      {
+        Location location = element_MyExt.location;
+        expect(location.offset, testCode.indexOf('MyExt on'));
+        expect(location.length, 'MyExt'.length);
+      }
+      expect(element_MyExt.parameters, null);
+      expect(element_MyExt.returnType, null);
+      // StringUtilities children
+      List<Outline> outlines_MyExt = outline_MyExt.children;
+      expect(outlines_MyExt, hasLength(2));
+    }
+  }
+
+  test_extension_unnamed() async {
+    createAnalysisOptionsFile(experiments: [EnableString.extension_methods]);
+    Outline unitOutline = await _computeOutline('''
+extension on String {
+  int get halfLength => length ~/ 2;
+  void writeOn(StringBuffer b) {
+    b.write(this);
+  }
+}
+''');
+    List<Outline> topOutlines = unitOutline.children;
+    expect(topOutlines, hasLength(1));
+    // MyExt
+    {
+      Outline outline_MyExt = topOutlines[0];
+      Element element_MyExt = outline_MyExt.element;
+      expect(element_MyExt.kind, ElementKind.EXTENSION);
+      expect(element_MyExt.name, '');
+      {
+        Location location = element_MyExt.location;
+        expect(location.offset, testCode.indexOf('String'));
+        expect(location.length, 'String'.length);
+      }
+      expect(element_MyExt.parameters, null);
+      expect(element_MyExt.returnType, null);
+      // StringUtilities children
+      List<Outline> outlines_MyExt = outline_MyExt.children;
+      expect(outlines_MyExt, hasLength(2));
+    }
+  }
+
   test_genericTypeAlias_incomplete() async {
     Outline unitOutline = await _computeOutline('''
 typedef F = Object;
diff --git a/pkg/analysis_server/tool/spec/generated/java/types/ElementKind.java b/pkg/analysis_server/tool/spec/generated/java/types/ElementKind.java
index 2ac5f3ed310..5fe4e7b8fa6 100644
--- a/pkg/analysis_server/tool/spec/generated/java/types/ElementKind.java
+++ b/pkg/analysis_server/tool/spec/generated/java/types/ElementKind.java
@@ -29,6 +29,8 @@ public class ElementKind {
 
   public static final String ENUM_CONSTANT = "ENUM_CONSTANT";
 
+  public static final String EXTENSION = "EXTENSION";
+
   public static final String FIELD = "FIELD";
 
   public static final String FILE = "FILE";
diff --git a/pkg/analyzer/lib/src/dart/ast/ast.dart b/pkg/analyzer/lib/src/dart/ast/ast.dart
index 623d44ac443..736f66abf20 100644
--- a/pkg/analyzer/lib/src/dart/ast/ast.dart
+++ b/pkg/analyzer/lib/src/dart/ast/ast.dart
@@ -3906,7 +3906,7 @@ class ExtensionDeclarationImpl extends CompilationUnitMemberImpl
   }
 
   @override
-  Token get firstTokenAfterCommentAndMetadata => name.beginToken;
+  Token get firstTokenAfterCommentAndMetadata => extensionKeyword;
 
   @override
   NodeList<ClassMember> get members => _members;
diff --git a/pkg/analyzer_plugin/doc/api.html b/pkg/analyzer_plugin/doc/api.html
index 910ab7aba83..2390ce261e8 100644
--- a/pkg/analyzer_plugin/doc/api.html
+++ b/pkg/analyzer_plugin/doc/api.html
@@ -1291,7 +1291,7 @@ a:focus, a:hover {
       An enumeration of the kinds of elements.
     </p>
     
-  <dl><dt class="value">CLASS</dt><dt class="value">CLASS_TYPE_ALIAS</dt><dt class="value">COMPILATION_UNIT</dt><dt class="value">CONSTRUCTOR</dt><dt class="value">CONSTRUCTOR_INVOCATION</dt><dt class="value">ENUM</dt><dt class="value">ENUM_CONSTANT</dt><dt class="value">FIELD</dt><dt class="value">FILE</dt><dt class="value">FUNCTION</dt><dt class="value">FUNCTION_INVOCATION</dt><dt class="value">FUNCTION_TYPE_ALIAS</dt><dt class="value">GETTER</dt><dt class="value">LABEL</dt><dt class="value">LIBRARY</dt><dt class="value">LOCAL_VARIABLE</dt><dt class="value">METHOD</dt><dt class="value">MIXIN</dt><dt class="value">PARAMETER</dt><dt class="value">PREFIX</dt><dt class="value">SETTER</dt><dt class="value">TOP_LEVEL_VARIABLE</dt><dt class="value">TYPE_PARAMETER</dt><dt class="value">UNIT_TEST_GROUP</dt><dt class="value">UNIT_TEST_TEST</dt><dt class="value">UNKNOWN</dt></dl></dd><dt class="typeDefinition"><a name="type_FilePath">FilePath: String</a></dt><dd>
+  <dl><dt class="value">CLASS</dt><dt class="value">CLASS_TYPE_ALIAS</dt><dt class="value">COMPILATION_UNIT</dt><dt class="value">CONSTRUCTOR</dt><dt class="value">CONSTRUCTOR_INVOCATION</dt><dt class="value">ENUM</dt><dt class="value">ENUM_CONSTANT</dt><dt class="value">EXTENSION</dt><dt class="value">FIELD</dt><dt class="value">FILE</dt><dt class="value">FUNCTION</dt><dt class="value">FUNCTION_INVOCATION</dt><dt class="value">FUNCTION_TYPE_ALIAS</dt><dt class="value">GETTER</dt><dt class="value">LABEL</dt><dt class="value">LIBRARY</dt><dt class="value">LOCAL_VARIABLE</dt><dt class="value">METHOD</dt><dt class="value">MIXIN</dt><dt class="value">PARAMETER</dt><dt class="value">PREFIX</dt><dt class="value">SETTER</dt><dt class="value">TOP_LEVEL_VARIABLE</dt><dt class="value">TYPE_PARAMETER</dt><dt class="value">UNIT_TEST_GROUP</dt><dt class="value">UNIT_TEST_TEST</dt><dt class="value">UNKNOWN</dt></dl></dd><dt class="typeDefinition"><a name="type_FilePath">FilePath: String</a></dt><dd>
     
     <p>
       The absolute, normalized path of a file.
diff --git a/pkg/analyzer_plugin/lib/protocol/protocol_common.dart b/pkg/analyzer_plugin/lib/protocol/protocol_common.dart
index 82891af510b..75ea6641a52 100644
--- a/pkg/analyzer_plugin/lib/protocol/protocol_common.dart
+++ b/pkg/analyzer_plugin/lib/protocol/protocol_common.dart
@@ -1903,6 +1903,7 @@ class Element implements HasToJson {
  *   CONSTRUCTOR_INVOCATION
  *   ENUM
  *   ENUM_CONSTANT
+ *   EXTENSION
  *   FIELD
  *   FILE
  *   FUNCTION
@@ -1944,6 +1945,8 @@ class ElementKind implements Enum {
 
   static const ElementKind ENUM_CONSTANT = const ElementKind._("ENUM_CONSTANT");
 
+  static const ElementKind EXTENSION = const ElementKind._("EXTENSION");
+
   static const ElementKind FIELD = const ElementKind._("FIELD");
 
   static const ElementKind FILE = const ElementKind._("FILE");
@@ -2000,6 +2003,7 @@ class ElementKind implements Enum {
     CONSTRUCTOR_INVOCATION,
     ENUM,
     ENUM_CONSTANT,
+    EXTENSION,
     FIELD,
     FILE,
     FUNCTION,
@@ -2042,6 +2046,8 @@ class ElementKind implements Enum {
         return ENUM;
       case "ENUM_CONSTANT":
         return ENUM_CONSTANT;
+      case "EXTENSION":
+        return EXTENSION;
       case "FIELD":
         return FIELD;
       case "FILE":
diff --git a/pkg/analyzer_plugin/test/integration/support/protocol_matchers.dart b/pkg/analyzer_plugin/test/integration/support/protocol_matchers.dart
index d7aeda74e09..58cb27cec7d 100644
--- a/pkg/analyzer_plugin/test/integration/support/protocol_matchers.dart
+++ b/pkg/analyzer_plugin/test/integration/support/protocol_matchers.dart
@@ -271,6 +271,7 @@ final Matcher isElement =
  *   CONSTRUCTOR_INVOCATION
  *   ENUM
  *   ENUM_CONSTANT
+ *   EXTENSION
  *   FIELD
  *   FILE
  *   FUNCTION
@@ -300,6 +301,7 @@ final Matcher isElementKind = new MatchesEnum("ElementKind", [
   "CONSTRUCTOR_INVOCATION",
   "ENUM",
   "ENUM_CONSTANT",
+  "EXTENSION",
   "FIELD",
   "FILE",
   "FUNCTION",
diff --git a/pkg/analyzer_plugin/tool/spec/common_types_spec.html b/pkg/analyzer_plugin/tool/spec/common_types_spec.html
index aac0a52a51f..812c4492390 100644
--- a/pkg/analyzer_plugin/tool/spec/common_types_spec.html
+++ b/pkg/analyzer_plugin/tool/spec/common_types_spec.html
@@ -530,6 +530,7 @@
       <value><code>CONSTRUCTOR_INVOCATION</code></value>
       <value><code>ENUM</code></value>
       <value><code>ENUM_CONSTANT</code></value>
+      <value><code>EXTENSION</code></value>
       <value><code>FIELD</code></value>
       <value><code>FILE</code></value>
       <value><code>FUNCTION</code></value>