Stop creating unnecessary Source

pkg/analyzer_plugin/lib/plugin/plugin.dart

 // Copyright (c) 2017, 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.
 
 import 'dart:async';
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/physical_file_system.dart';
 import 'package:analyzer/src/dart/analysis/driver.dart'
     show AnalysisDriverGeneric, AnalysisDriverScheduler;
 import 'package:analyzer/src/dart/analysis/file_state.dart';
 import 'package:analyzer/src/generated/sdk.dart';
-import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer_plugin/channel/channel.dart';
 import 'package:analyzer_plugin/protocol/protocol.dart';
 import 'package:analyzer_plugin/protocol/protocol_common.dart';
 import 'package:analyzer_plugin/protocol/protocol_constants.dart';
 import 'package:analyzer_plugin/protocol/protocol_generated.dart';
 import 'package:analyzer_plugin/src/protocol/protocol_internal.dart';
 import 'package:analyzer_plugin/src/utilities/null_string_sink.dart';
 import 'package:analyzer_plugin/utilities/subscriptions/subscription_manager.dart';
 import 'package:front_end/src/base/performace_logger.dart';
 import 'package:front_end/src/incremental/byte_store.dart';
@@ skipping 308 matching lines @@
 
   /**
    * Handle an 'analysis.updateContent' request. Most subclasses should not
    * override this method, but should instead use the [contentCache] to access
    * the current content of overlaid files.
    */
   Future<AnalysisUpdateContentResult> handleAnalysisUpdateContent(
       AnalysisUpdateContentParams parameters) async {
     Map<String, Object> files = parameters.files;
     files.forEach((String filePath, Object overlay) {
-      // We don't need to get the correct URI because only the full path is
-      // used by the contentCache.
-      Source source = resourceProvider.getFile(filePath).createSource();
       if (overlay is AddContentOverlay) {
-        fileContentOverlay[source.fullName] = overlay.content;
+        fileContentOverlay[filePath] = overlay.content;
       } else if (overlay is ChangeContentOverlay) {
-        String fileName = source.fullName;
-        String oldContents = fileContentOverlay[fileName];
+        String oldContents = fileContentOverlay[filePath];
         String newContents;
         if (oldContents == null) {
           // The server should only send a ChangeContentOverlay if there is
           // already an existing overlay for the source.
           throw new RequestFailure(
               RequestErrorFactory.invalidOverlayChangeNoContent());
         }
         try {
           newContents = SourceEdit.applySequence(oldContents, overlay.edits);
         } on RangeError {
           throw new RequestFailure(
               RequestErrorFactory.invalidOverlayChangeInvalidEdit());
         }
-        fileContentOverlay[fileName] = newContents;
+        fileContentOverlay[filePath] = newContents;
       } else if (overlay is RemoveContentOverlay) {
-        fileContentOverlay[source.fullName] = null;
+        fileContentOverlay[filePath] = null;
       }
       contentChanged(filePath);
     });
     return new AnalysisUpdateContentResult();
   }
 
   /**
    * Handle a 'completion.getSuggestions' request.
    */
   Future<CompletionGetSuggestionsResult> handleCompletionGetSuggestions(
@@ skipping 213 matching lines @@
       response = new Response(id, requestTime,
           error: new RequestError(
               RequestErrorCode.PLUGIN_ERROR, exception.toString(),
               stackTrace: stackTrace.toString()));
     }
     if (response != null) {
       _channel.sendResponse(response);
     }
   }
 }