Move Range code to gfx.

ui/base/range/range_mac.mm

-// 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 "ui/base/range/range.h"
-
-#include <limits>
-
-#include "base/logging.h"
-
-namespace ui {
-
-Range::Range(const NSRange& range) {
-  *this = range;
-}
-
-Range& Range::operator=(const NSRange& range) {
-  if (range.location == NSNotFound) {
-    DCHECK_EQ(0U, range.length);
-    *this = InvalidRange();
-  } else {
-    set_start(range.location);
-    // Don't overflow |end_|.
-    DCHECK_LE(range.length, std::numeric_limits<size_t>::max() - start());
-    set_end(start() + range.length);
-  }
-  return *this;
-}
-
-NSRange Range::ToNSRange() const {
-  if (!IsValid())
-    return NSMakeRange(NSNotFound, 0);
-  return NSMakeRange(GetMin(), length());
-}
-
-}  // namespace gfx