Update ALLOW_THIS_IN_INITIALIZER_LIST macro to reflect its deprecatation.

base/compiler_specific.h

 // Copyright (c) 2012 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.
 
 #ifndef BASE_COMPILER_SPECIFIC_H_
 #define BASE_COMPILER_SPECIFIC_H_
 
 #include "build/build_config.h"
 
 #if defined(COMPILER_MSVC)
@@ skipping 22 matching lines @@
 // remains in effect until popped by MSVC_POP_WARNING().  Use 0 to disable all
 // warnings.
 #define MSVC_PUSH_WARNING_LEVEL(n) __pragma(warning(push, n))
 
 // Pop effects of innermost MSVC_PUSH_* macro.
 #define MSVC_POP_WARNING() __pragma(warning(pop))
 
 #define MSVC_DISABLE_OPTIMIZE() __pragma(optimize("", off))
 #define MSVC_ENABLE_OPTIMIZE() __pragma(optimize("", on))
 
-// Allows |this| to be passed as an argument in constructor initializer lists.
-// This uses push/pop instead of the seemingly simpler suppress feature to avoid
-// having the warning be disabled for more than just |code|.
+// DEPRECATED
 //
-// Example usage:
-// Foo::Foo() : x(NULL), ALLOW_THIS_IN_INITIALIZER_LIST(y(this)), z(3) {}
+// Prior to r83840 this was used to supress warning C4355 when using |this| as
+// an argument in constructor initializer lists:
+// http://msdn.microsoft.com/en-us/library/3c594ae3(VS.80).aspx
 //
-// Compiler warning C4355: 'this': used in base member initializer list:
-// http://msdn.microsoft.com/en-us/library/3c594ae3(VS.80).aspx
-#define ALLOW_THIS_IN_INITIALIZER_LIST(code) MSVC_PUSH_DISABLE_WARNING(4355) \
-                                             code \
-                                             MSVC_POP_WARNING()
+// C4355 is supressed globally during compilation and existing uses of this
+// macro should be removed. Refer to http://crbug.com/234765 for details.
+#define ALLOW_THIS_IN_INITIALIZER_LIST(code) code
 
 // Allows exporting a class that inherits from a non-exported base class.
 // This uses suppress instead of push/pop because the delimiter after the
 // declaration (either "," or "{") has to be placed before the pop macro.
 //
 // Example usage:
 // class EXPORT_API Foo : NON_EXPORTED_BASE(public Bar) {
 //
 // MSVC Compiler warning C4275:
 // non dll-interface class 'Bar' used as base for dll-interface class 'Foo'.
@@ skipping 110 matching lines @@
 
 // Mark a memory region fully initialized.
 // Use this to annotate code that deliberately reads uninitialized data, for
 // example a GC scavenging root set pointers from the stack.
 #define MSAN_UNPOISON(p, s)  __msan_unpoison(p, s)
 #else  // MEMORY_SANITIZER
 #define MSAN_UNPOISON(p, s)
 #endif  // MEMORY_SANITIZER
 
 #endif  // BASE_COMPILER_SPECIFIC_H_