Move the use of 'multi-root' out of the FE

Change-Id: If26e4da18d4379041927e100e471a381f5979126
Reviewed-on: https://dart-review.googlesource.com/30600
Commit-Queue: Sigmund Cherem <[email protected]>
Reviewed-by: Jake Macdonald <[email protected]>

Author: sigmundch

pkg/dev_compiler/lib/src/kernel/command.dart

@@ -8,7 +8,9 @@ import 'dart:io';
 
 import 'package:args/args.dart';
 import 'package:dev_compiler/src/kernel/target.dart';
+import 'package:front_end/src/api_prototype/physical_file_system.dart';
 import 'package:front_end/src/api_unstable/ddc.dart' as fe;
+import 'package:front_end/src/multi_root_file_system.dart';
 import 'package:kernel/core_types.dart';
 import 'package:kernel/kernel.dart';
 import 'package:path/path.dart' as path;
@@ -122,12 +124,24 @@ Future<CompilerResult> _compile(List<String> args,
     }
   }
 
+  // To make the output .dill agnostic of the current working directory,
+  // we use a custom-uri scheme for all app URIs (these are files outside the
+  // lib folder). The following [FileSystem] will resolve those references to
+  // the correct location and keeps the real file location hidden from the
+  // front end.
+  // TODO(sigmund): technically we don't need a "multi-root" file system,
+  // because we are providing a single root, the alternative here is to
+  // implement a new file system with a single root instead.
+  var fileSystem = new MultiRootFileSystem(
+      'org-dartlang-app', [Uri.base], PhysicalFileSystem.instance);
+
   compilerState = await fe.initializeCompiler(
       compilerState,
       path.toUri(sdkSummaryPath),
       path.toUri(packageFile),
       summaryUris,
-      new DevCompilerTarget());
+      new DevCompilerTarget(),
+      fileSystem: fileSystem);
   fe.DdcResult result = await fe.compile(compilerState, inputs, errorHandler);
   if (result == null || !succeeded) {
     return new CompilerResult(compilerState, false);

pkg/front_end/lib/src/api_unstable/ddc.dart

@@ -4,10 +4,10 @@
 
 import 'dart:async' show Future;
 
+import 'package:front_end/src/api_prototype/file_system.dart';
 import 'package:front_end/src/api_prototype/physical_file_system.dart';
 import 'package:front_end/src/base/processed_options.dart';
 import 'package:front_end/src/kernel_generator_impl.dart';
-import 'package:front_end/src/multi_root_file_system.dart';
 import 'package:kernel/kernel.dart' show Program;
 import 'package:kernel/target/targets.dart' show Target;
 
@@ -30,7 +30,8 @@ Future<InitializedCompilerState> initializeCompiler(
     Uri sdkSummary,
     Uri packagesFile,
     List<Uri> inputSummaries,
-    Target target) async {
+    Target target,
+    {FileSystem fileSystem}) async {
   inputSummaries.sort((a, b) => a.toString().compareTo(b.toString()));
   bool listEqual(List<Uri> a, List<Uri> b) {
     if (a.length != b.length) return false;
@@ -59,23 +60,12 @@ Future<InitializedCompilerState> initializeCompiler(
     return oldState;
   }
 
-  // To make the output .dill agnostic of the current working directory,
-  // we use a custom-uri scheme for all app URIs (these are files outside the
-  // lib folder). The following [FileSystem] will resolve those references to
-  // the correct location and keeps the real file location hidden from the
-  // front end.
-  // TODO(sigmund): technically we don't need a "multi-root" file system,
-  // because we are providing a single root, the alternative here is to
-  // implement a new file system with a single root instead.
-  var fileSystem = new MultiRootFileSystem(
-      'org-dartlang-app', [Uri.base], PhysicalFileSystem.instance);
-
   CompilerOptions options = new CompilerOptions()
     ..sdkSummary = sdkSummary
     ..packagesFileUri = packagesFile
     ..inputSummaries = inputSummaries
     ..target = target
-    ..fileSystem = fileSystem
+    ..fileSystem = fileSystem ?? PhysicalFileSystem.instance
     ..chaseDependencies = true
     ..reportMessages = true;