Make all allocation of external arrays used for IO use the IOBuffer class

runtime/bin/dartutils.cc

Index: runtime/bin/dartutils.cc
diff --git a/runtime/bin/dartutils.cc b/runtime/bin/dartutils.cc
index 339b036869130f4aa9e1a7f286b43844905ddbc6..6257db653b094b879a50c19944d3bc52e1f99bdb 100644
--- a/runtime/bin/dartutils.cc
+++ b/runtime/bin/dartutils.cc
@@ -7,6 +7,7 @@
 #include "bin/extensions.h"
 #include "bin/directory.h"
 #include "bin/file.h"
+#include "bin/io_buffer.h"
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/globals.h"
@@ -671,6 +672,20 @@ Dart_CObject* CObject::NewExternalUint8Array(int64_t length,
 }
 
 
+Dart_CObject* CObject::NewIOBuffer(int64_t length) {
+  uint8_t* data = IOBuffer::Allocate(length);
+  return NewExternalUint8Array(length, data, data, IOBuffer::Free);
+}
+
+
+void CObject::FreeIOBufferData(Dart_CObject* cobject) {
+  ASSERT(cobject->type == Dart_CObject::kExternalUint8Array);
+  cobject->value.as_external_byte_array.callback(
+      cobject->value.as_external_byte_array.peer);
+  cobject->value.as_external_byte_array.data = NULL;
+}
+
+
 static int kArgumentError = 1;
 static int kOSError = 2;
 static int kFileClosedError = 3;