Remove MOJO_STATIC_CONST_MEMBER_DEFINITION.

mojo/public/cpp/system/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.
 
 // Define a set of C++ specific macros.
 // Mojo C++ API users can assume that mojo/public/cpp/system/macros.h
 // includes mojo/public/c/system/macros.h.
 
 #ifndef MOJO_PUBLIC_CPP_SYSTEM_MACROS_H_
 #define MOJO_PUBLIC_CPP_SYSTEM_MACROS_H_
@@ skipping 46 matching lines @@
 // by default.)
 #define MOJO_MOVE_ONLY_TYPE(type)                                    \
  public:                                                             \
   type&& Pass() MOJO_WARN_UNUSED_RESULT { return std::move(*this); } \
   typedef void MoveOnlyTypeForCPP03;                                 \
                                                                      \
  private:                                                            \
   type(const type&) = delete;                                        \
   void operator=(const type&) = delete
 
-// The C++ standard requires that static const members have an out-of-class
-// definition (in a single compilation unit), but MSVC chokes on this (when
-// language extensions, which are required, are enabled). (You're only likely to
-// notice the need for a definition if you take the address of the member or,
-// more commonly, pass it to a function that takes it as a reference argument --
-// probably an STL function.) This macro makes MSVC do the right thing. See
-// http://msdn.microsoft.com/en-us/library/34h23df8(v=vs.100).aspx for more
-// information. This workaround does not appear to be necessary after VS2015.
-// Use like:
-//
-// In the .h file:
-//   struct Foo {
-//     static const int kBar = 5;
-//   };
-//
-// In the .cc file:
-//   MOJO_STATIC_CONST_MEMBER_DEFINITION const int Foo::kBar;
-#if defined(_MSC_VER) && _MSC_VER < 1900
-#define MOJO_STATIC_CONST_MEMBER_DEFINITION __declspec(selectany)
-#else
-#define MOJO_STATIC_CONST_MEMBER_DEFINITION
-#endif
-
 namespace mojo {
 
 // Used to explicitly mark the return value of a function as unused. (Use this
 // if you are really sure you don't want to do anything with the return value of
 // a function marked with |MOJO_WARN_UNUSED_RESULT|.
 template <typename T>
 inline void ignore_result(const T&) {
 }
 
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_SYSTEM_MACROS_H_