Move embedder locator and convert context builder to use the new API

pkg/analyzer/lib/source/embedder.dart

Index: pkg/analyzer/lib/source/embedder.dart
diff --git a/pkg/analyzer/lib/source/embedder.dart b/pkg/analyzer/lib/source/embedder.dart
index 56abc6a586c848014abadeae93ef46263b12962d..0dd84c0784eb1fb21c9d6b2391e7eec1b4ce9a4d 100644
--- a/pkg/analyzer/lib/source/embedder.dart
+++ b/pkg/analyzer/lib/source/embedder.dart
@@ -19,6 +19,8 @@ import 'package:analyzer/src/generated/source_io.dart' show FileBasedSource;
 import 'package:analyzer/src/summary/idl.dart';
 import 'package:yaml/yaml.dart';
 
+export 'package:analyzer/src/context/builder.dart' show EmbedderYamlLocator;
+
 const String _DART_COLON_PREFIX = 'dart:';
 const String _EMBEDDED_LIB_MAP_KEY = 'embedded_libs';
 
@@ -175,74 +177,3 @@ class EmbedderUriResolver implements DartUriResolver {
     return sdkSource?.uri;
   }
 }
-
-/// Given a packageMap, check in each package's lib directory for the
-/// existence of an `_embedder.yaml` file. If the file contains a top level
-/// YamlMap, it will be added to the [embedderYamls] map.
-class EmbedderYamlLocator {
-  static const String EMBEDDER_FILE_NAME = '_embedder.yaml';
-
-  /// Map from package's library directory to the parsed YamlMap.
-  final Map<Folder, YamlMap> embedderYamls = new HashMap<Folder, YamlMap>();
-
-  EmbedderYamlLocator(Map<String, List<Folder>> packageMap) {
-    if (packageMap != null) {
-      _processPackageMap(packageMap);
-    }
-  }
-
-  /// Programatically add an _embedder.yaml mapping.
-  void addEmbedderYaml(Folder libDir, String embedderYaml) {
-    _processEmbedderYaml(libDir, embedderYaml);
-  }
-
-  void refresh(Map<String, List<Folder>> packageMap) {
-    // Clear existing.
-    embedderYamls.clear();
-    if (packageMap != null) {
-      _processPackageMap(packageMap);
-    }
-  }
-
-  /// Given the yaml for an embedder ([embedderYaml]) and a folder
-  /// ([libDir]), setup the uri mapping.
-  void _processEmbedderYaml(Folder libDir, String embedderYaml) {
-    YamlNode yaml;
-    try {
-      yaml = loadYaml(embedderYaml);
-    } catch (_) {
-      return;
-    }
-    if (yaml is! YamlMap) {
-      return;
-    }
-    embedderYamls[libDir] = yaml;
-  }
-
-  /// Given a package [name] and a list of folders ([libDirs]),
-  /// add any found `_embedder.yaml` files.
-  void _processPackage(String name, List<Folder> libDirs) {
-    for (Folder libDir in libDirs) {
-      String embedderYaml = _readEmbedderYaml(libDir);
-      if (embedderYaml != null) {
-        _processEmbedderYaml(libDir, embedderYaml);
-      }
-    }
-  }
-
-  void _processPackageMap(Map<String, List<Folder>> packageMap) {
-    packageMap.forEach(_processPackage);
-  }
-
-  /// Read the contents of [libDir]/[EMBEDDER_FILE_NAME] as a string.
-  /// Returns null if the file doesn't exist.
-  String _readEmbedderYaml(Folder libDir) {
-    File file = libDir.getChild(EMBEDDER_FILE_NAME);
-    try {
-      return file.readAsStringSync();
-    } on FileSystemException {
-      // File can't be read.
-      return null;
-    }
-  }
-}