base: Remove gcc and msvs workaround limitations for arraysize template magic.

base/macros.h

 // Copyright 2014 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.
 
 // This file contains macros and macro-like constructs (e.g., templates) that
 // are commonly used throughout Chromium source. (It may also contain things
 // that are closely related to things that are commonly used that belong in this
 // file.)
 
 #ifndef BASE_MACROS_H_
@@ skipping 34 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(TypeName)
 
 // The arraysize(arr) macro returns the # of elements in an array arr.
 // The expression is a compile-time constant, and therefore can be
 // used in defining new arrays, for example.  If you use arraysize on
 // a pointer by mistake, you will get a compile-time error.
 
 // This template function declaration is used in defining arraysize.
 // Note that the function doesn't need an implementation, as we only
 // use its type.
-template <typename T, size_t N>
-char (&ArraySizeHelper(T (&array)[N]))[N];
-
-// That gcc wants both of these prototypes seems mysterious. VC, for
-// its part, can't decide which to use (another mystery). Matching of
-// template overloads: the final frontier.
-#ifndef _MSC_VER
-template <typename T, size_t N>
-char (&ArraySizeHelper(const T (&array)[N]))[N];
-#endif
-
-#define arraysize(array) (sizeof(::ArraySizeHelper(array)))
+template <typename T, size_t N> char (&ArraySizeHelper(T (&array)[N]))[N];
+#define arraysize(array) (sizeof(ArraySizeHelper(array)))
 
 
 // Use implicit_cast as a safe version of static_cast or const_cast
 // for upcasting in the type hierarchy (i.e. casting a pointer to Foo
 // to a pointer to SuperclassOfFoo or casting a pointer to Foo to
 // a const pointer to Foo).
 // When you use implicit_cast, the compiler checks that the cast is safe.
 // Such explicit implicit_casts are necessary in surprisingly many
 // situations where C++ demands an exact type match instead of an
 // argument type convertible to a target type.
@@ skipping 122 matching lines @@
 
 // Use these to declare and define a static local variable (static T;) so that
 // it is leaked so that its destructors are not called at exit. If you need
 // thread-safe initialization, use base/lazy_instance.h instead.
 #define CR_DEFINE_STATIC_LOCAL(type, name, arguments) \
   static type& name = *new type arguments
 
 }  // base
 
 #endif  // BASE_MACROS_H_