Refactor and cleanup VirtualMemory.

test/cctest/test-code-stubs-arm.cc

Index: test/cctest/test-code-stubs-arm.cc
diff --git a/test/cctest/test-code-stubs-arm.cc b/test/cctest/test-code-stubs-arm.cc
index c99433edad4c281b3a1c2b2e5b14dd772567c432..b4d23a4e06851d6429ecaec0b31cfb1a70ffa1d7 100644
--- a/test/cctest/test-code-stubs-arm.cc
+++ b/test/cctest/test-code-stubs-arm.cc
@@ -47,9 +47,10 @@ ConvertDToIFunc MakeConvertDToIFuncTrampoline(Isolate* isolate,
                                               bool inline_fastpath) {
   // Allocate an executable page of memory.
   size_t actual_size;
-  byte* buffer = static_cast<byte*>(OS::Allocate(Assembler::kMinimalBufferSize,
-                                                 &actual_size,
-                                                 true));
+  byte* buffer = static_cast<byte*>(VirtualMemory::AllocateRegion(
+          Assembler::kMinimalBufferSize,
+          &actual_size,
+          VirtualMemory::EXECUTABLE));
   CHECK(buffer);
   HandleScope handles(isolate);
   MacroAssembler masm(isolate, buffer, static_cast<int>(actual_size));