Port more String and HashMap usages

sky/shell/dart/dart_library_provider_files.cc

Index: sky/shell/dart/dart_library_provider_files.cc
diff --git a/sky/shell/dart/dart_library_provider_files.cc b/sky/shell/dart/dart_library_provider_files.cc
index 4c0e267ae0e1f7df8abf1b03080a94d694749a3b..2bed8e8e9e3e175127ec82d6558bb7844e8553a5 100644
--- a/sky/shell/dart/dart_library_provider_files.cc
+++ b/sky/shell/dart/dart_library_provider_files.cc
@@ -50,12 +50,12 @@ DartLibraryProviderFiles::~DartLibraryProviderFiles() {
 }
 
 void DartLibraryProviderFiles::GetLibraryAsStream(
-    const String& name,
+    const std::string& name,
     blink::DataPipeConsumerCallback callback) {
   mojo::DataPipe pipe;
   callback.Run(pipe.consumer_handle.Pass());
 
-  base::FilePath source(name.toUTF8());
+  base::FilePath source(name);
   scoped_refptr<base::TaskRunner> runner =
       base::WorkerPool::GetTaskRunner(true);
   mojo::common::CopyFromFile(source, pipe.producer_handle.Pass(), 0,