Consolidate RenderText adjacent word selection model code.

ui/gfx/render_text.cc

Index: ui/gfx/render_text.cc
diff --git a/ui/gfx/render_text.cc b/ui/gfx/render_text.cc
index 91f9f42bd89ad69dad47646e52c08516e9cad394..a80f0e0e9634d3ebdbf76b835a1ea615f3672202 100644
--- a/ui/gfx/render_text.cc
+++ b/ui/gfx/render_text.cc
@@ -789,6 +789,49 @@ SelectionModel RenderText::GetAdjacentSelectionModel(
   return AdjacentWordSelectionModel(current, direction);
 }
 
+SelectionModel RenderText::AdjacentWordSelectionModel(
+    const SelectionModel& selection,
+    VisualCursorDirection direction) {
+  if (obscured())
+    return EdgeSelectionModel(direction);
+
+  base::i18n::BreakIterator iter(text(), base::i18n::BreakIterator::BREAK_WORD);
+  bool success = iter.Init();
+  DCHECK(success);
+  if (!success)
+    return selection;
+
+  size_t pos = 0;
+  // TODO(msw): Cache a list of word breaks or add WordIterator functionality to
+  // start from supplied indices and to iterate backward for better performance.
+  if (direction == CURSOR_RIGHT) {
+    pos = std::min(selection.caret_pos() + 1, text().length());
+    while (iter.Advance()) {
+      pos = iter.pos();
+      if (iter.IsWord() && pos > selection.caret_pos())
+        break;
+    }
+  } else {
+    pos = std::max<int>(selection.caret_pos() - 1, 0);
+    while (iter.Advance()) {
+      if (iter.IsWord()) {
+        size_t begin = iter.pos() - iter.GetString().length();
+        if (begin == selection.caret_pos()) {
+          // The cursor is at a word beginning; move it to the previous word.
+          break;
+        } else if (iter.pos() >= selection.caret_pos()) {
+          // The cursor is at a word middle or end; move it to its beginning.
+          pos = begin;
+          break;
+        } else {
+          pos = iter.pos() - iter.GetString().length();
+        }
+      }
+    }
+  }
+  return SelectionModel(pos, CURSOR_FORWARD);
+}
+
 SelectionModel RenderText::EdgeSelectionModel(
     VisualCursorDirection direction) {
   if (direction == GetVisualDirectionOfLogicalEnd())