Add an "api signature" to summaries.

pkg/analyzer/lib/src/summary/summarize_elements.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library serialization.elements;
 
 import 'dart:convert';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/member.dart';
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/generated/resolver.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/utilities_dart.dart';
+import 'package:analyzer/src/summary/flat_buffers.dart';
 import 'package:analyzer/src/summary/format.dart';
 import 'package:analyzer/src/summary/idl.dart';
 import 'package:analyzer/src/summary/name_filter.dart';
 import 'package:analyzer/src/summary/summarize_const_expr.dart';
 import 'package:convert/convert.dart';
 import 'package:crypto/crypto.dart';
 import 'package:path/path.dart' as path;
 
 /**
  * Serialize all the elements in [lib] to a summary using [ctx] as the context
@@ skipping 157 matching lines @@
       String uri, UnlinkedUnitBuilder unit, String hash) {
     _unlinkedUnitUris.add(uri);
     _unlinkedUnits.add(unit);
     _unlinkedUnitHashes?.add(hash);
   }
 
   /**
    * Assemble a new [PackageBundleBuilder] using the gathered information.
    */
   PackageBundleBuilder assemble() {
-    return new PackageBundleBuilder(
+    PackageBundleBuilder packageBundle = new PackageBundleBuilder(
         linkedLibraryUris: _linkedLibraryUris,
         linkedLibraries: _linkedLibraries,
         unlinkedUnitUris: _unlinkedUnitUris,
         unlinkedUnits: _unlinkedUnits,
         unlinkedUnitHashes: _unlinkedUnitHashes,
         majorVersion: currentMajorVersion,
         minorVersion: currentMinorVersion);
+    ApiSignature apiSignature = new ApiSignature();
+    packageBundle.collectApiSignature(apiSignature);
+    packageBundle.apiSignature = apiSignature.toHex();
+    return packageBundle;
   }
 
   /**
    * Serialize the library with the given [element].
    */
   void serializeLibraryElement(LibraryElement element) {
     String uri = element.source.uri.toString();
     LibrarySerializationResult libraryResult = serializeLibrary(
         element,
         element.context.typeProvider,
@@ skipping 1462 matching lines @@
       exportNames.add(new LinkedExportNameBuilder(
           name: name,
           dependency: serializeDependency(dependentLibrary),
           unit: unit,
           kind: kind));
     }
     pb.exportNames = exportNames;
     return pb;
   }
 }