[dart:io] Adds ProcessInfo.{max,current}Rss. Adds OS::MaxRSS on Fuchsia.

runtime/bin/process.cc

Index: runtime/bin/process.cc
diff --git a/runtime/bin/process.cc b/runtime/bin/process.cc
index 80133289d3141ced18f0c5a6b77d6c58a02d28d7..50f4dd53f657edc2caed271c81dcaea603565183 100644
--- a/runtime/bin/process.cc
+++ b/runtime/bin/process.cc
@@ -366,6 +366,26 @@ void FUNCTION_NAME(StringToSystemEncoding)(Dart_NativeArguments args) {
   Dart_SetReturnValue(args, external_array);
 }
 
+
+void FUNCTION_NAME(ProcessInfo_CurrentRSS)(Dart_NativeArguments args) {
+  intptr_t current_rss = Process::CurrentRSS();
+  if (current_rss < 0) {
+    Dart_SetReturnValue(args, DartUtils::NewDartOSError());
+    return;
+  }
+  Dart_SetIntegerReturnValue(args, current_rss);
+}
+
+
+void FUNCTION_NAME(ProcessInfo_MaxRSS)(Dart_NativeArguments args) {
+  intptr_t max_rss = Process::MaxRSS();
+  if (max_rss < 0) {
+    Dart_SetReturnValue(args, DartUtils::NewDartOSError());
+    return;
+  }
+  Dart_SetIntegerReturnValue(args, max_rss);
+}
+
 }  // namespace bin
 }  // namespace dart