Revert "Remove spellcheck feedback."

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);
+}