Use volatile to prevent heap-to-stack promotion in an ASan test

sandbox/win/src/address_sanitizer_test.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdio.h>
 
 #include "base/environment.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
@@ skipping 22 matching lines @@
  protected:
   scoped_ptr<base::Environment> env_;
   bool had_asan_options_;
   std::string old_asan_options_;
 };
 
 SBOX_TESTS_COMMAND int AddressSanitizerTests_Report(int argc, wchar_t** argv) {
   // AddressSanitizer should detect an out of bounds write (heap buffer
   // overflow) in this code.
   volatile int idx = 42;
-  int *blah = new int[42];
+  int *volatile blah = new int[42];
   blah[idx] = 42;
   delete [] blah;
   return SBOX_TEST_FAILED;
 }
 
 TEST_F(AddressSanitizerTests, TestAddressSanitizer) {
   // This test is only supposed to work when using AddressSanitizer.
   // However, ASan/Win is not on the CQ yet, so compiler breakages may get into
   // the code unnoticed.  To avoid that, we compile this test in all Windows
   // builds, but only run the AddressSanitizer-specific part of the test when
@@ skipping 44 matching lines @@
           << "The stack trace doesn't have a correct filename:\n" << data;
     } else {
       LOG(WARNING) << "Pre-Vista versions are not supported.";
     }
   } else {
     LOG(WARNING) << "Not an AddressSanitizer build, skipping the run.";
   }
 }
 
 }