Cleanup in //runtime/bin

runtime/bin/extensions.cc

Index: runtime/bin/extensions.cc
diff --git a/runtime/bin/extensions.cc b/runtime/bin/extensions.cc
index eaed7bb38b1a2775e30c4563bab40295d2888a53..7fa06fd64524cbeed4cff47b0c2f58b7ec3d1a4a 100644
--- a/runtime/bin/extensions.cc
+++ b/runtime/bin/extensions.cc
@@ -6,12 +6,11 @@
 
 #include <stdio.h>
 
+#include "bin/dartutils.h"
+#include "bin/file.h"
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/globals.h"
-#include "bin/dartutils.h"
-#include "bin/file.h"
-
 
 namespace dart {
 namespace bin {
@@ -25,17 +24,15 @@ Dart_Handle Extensions::LoadExtension(const char* extension_directory,
     return Dart_NewApiError("Cannot load native extensions over http:");
   }
   const char* library_strings[] = { extension_directory, extension_file, NULL };
-  char* library_file = Concatenate(library_strings);
+  const char* library_file = Concatenate(library_strings);
   void* library_handle = LoadExtensionLibrary(library_file);
-  free(library_file);
   if (library_handle == NULL) {
     return GetError();
   }
 
   const char* strings[] = { extension_name, "_Init", NULL };
-  char* init_function_name = Concatenate(strings);
+  const char* init_function_name = Concatenate(strings);
   void* init_function = ResolveSymbol(library_handle, init_function_name);
-  free(init_function_name);
   Dart_Handle result = GetError();
   if (Dart_IsError(result)) {
     return result;
@@ -48,13 +45,13 @@ Dart_Handle Extensions::LoadExtension(const char* extension_directory,
 
 
 // Concatenates a NULL terminated array of strings.
-// The returned string must be freed.
-char* Extensions::Concatenate(const char** strings) {
+// The returned string is scope allocated.
+const char* Extensions::Concatenate(const char** strings) {
   int size = 1;  // null termination.
   for (int i = 0; strings[i] != NULL; i++) {
     size += strlen(strings[i]);
   }
-  char* result = reinterpret_cast<char*>(malloc(size));
+  char* result = reinterpret_cast<char*>(Dart_ScopeAllocate(size));
   int index = 0;
   for (int i = 0; strings[i] != NULL; i++) {
     index += snprintf(result + index, size - index, "%s", strings[i]);