Rename TranslateUri to UriTranslator, rename files, extract Impl.

pkg/front_end/lib/src/incremental_kernel_generator_impl.dart

Index: pkg/front_end/lib/src/incremental_kernel_generator_impl.dart
diff --git a/pkg/front_end/lib/src/incremental_kernel_generator_impl.dart b/pkg/front_end/lib/src/incremental_kernel_generator_impl.dart
index daff92492b7f5bf6d67378210c91de80962cfde9..be9371b06d0956100a808328c436f01a4db96425 100644
--- a/pkg/front_end/lib/src/incremental_kernel_generator_impl.dart
+++ b/pkg/front_end/lib/src/incremental_kernel_generator_impl.dart
@@ -14,7 +14,7 @@ import 'package:front_end/src/fasta/dill/dill_target.dart';
 import 'package:front_end/src/fasta/kernel/kernel_target.dart';
 import 'package:front_end/src/fasta/kernel/utils.dart';
 import 'package:front_end/src/fasta/ticker.dart';
-import 'package:front_end/src/fasta/translate_uri.dart';
+import 'package:front_end/src/fasta/uri_translator.dart';
 import 'package:front_end/src/incremental/byte_store.dart';
 import 'package:front_end/src/incremental/file_state.dart';
 import 'package:kernel/binary/ast_from_binary.dart';
@@ -39,7 +39,7 @@ class IncrementalKernelGeneratorImpl implements IncrementalKernelGenerator {
   final ProcessedOptions _options;
 
   /// The object that knows how to resolve "package:" and "dart:" URIs.
-  final TranslateUri _uriTranslator;
+  final UriTranslator _uriTranslator;
 
   /// The logger to report compilation progress.
   final PerformanceLog _logger;