windows: Fix a few things clang complains about.

base/allocator/allocator_shim.cc

 // Copyright (c) 2011 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 "base/allocator/allocator_shim.h"
 
 #include <config.h>
 #include "base/sysinfo.h"
 
 // When defined, different heap allocators can be used via an environment
@@ skipping 276 matching lines @@
   size_t primary_length = 0;
   getenv_s(&primary_length, NULL, 0, primary_name);
 
   size_t secondary_length = 0;
   char buffer[20];
   getenv_s(&secondary_length, buffer, sizeof(buffer), secondary_name);
   DCHECK_GT(sizeof(buffer), secondary_length);
   buffer[sizeof(buffer) - 1] = '\0';
 
   if (secondary_length || !primary_length) {
-    char* secondary_value = secondary_length ? buffer : "TCMALLOC";
+    const char* secondary_value = secondary_length ? buffer : "TCMALLOC";
     // Force renderer (or other subprocesses) to use secondary_value.
     int ret_val = _putenv_s(primary_name, secondary_value);
     DCHECK_EQ(0, ret_val);
   }
 #endif  // ENABLE_DYNAMIC_ALLOCATOR_SWITCHING
 }
 
 }  // namespace base.
 }  // namespace allocator.