[WIP][DO NOT LAND] Componentize spellcheck

chrome/browser/spellchecker/word_trimmer.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 "chrome/browser/spellchecker/word_trimmer.h"
-
-#include <algorithm>
-#include <vector>
-
-#include "base/i18n/break_iterator.h"
-
-base::string16 TrimWords(size_t* start,
-                         size_t end,
-                         const base::string16& text,
-                         size_t keep) {
-  if (*start > text.length() || *start > end)
-    return text;
-  base::i18n::BreakIterator iter(text, base::i18n::BreakIterator::BREAK_WORD);
-  if (!iter.Init())
-    return text;
-  // A circular buffer of the last |keep + 1| words seen before position |start|
-  // in |text|.
-  std::vector<size_t> word_offset(keep + 1, 0);
-  size_t first = std::string::npos;
-  size_t last = std::string::npos;
-  while (iter.Advance()) {
-    if (iter.IsWord()) {
-      word_offset[keep] = iter.prev();
-      if ((*start >= iter.prev() && *start < iter.pos()) ||
-          (end > iter.prev() && end <= iter.pos())) {
-        if (first == std::string::npos)
-          first = word_offset[0];
-        last = iter.pos();
-      }
-      if (first == std::string::npos) {
-        std::rotate(word_offset.begin(),
-                    word_offset.begin() + 1,
-                    word_offset.end());
-      }
-      if (iter.prev() > end && keep) {
-        last = iter.pos();
-        keep--;
-      }
-    }
-  }
-  if (first == std::string::npos)
-    return text;
-  *start -= first;
-  return text.substr(first, last - first);
-}