Move Editor::Transpose() out of Editor class

This patch moves |Editor::Transpose()| out of |Editor| class as preparation of
expanding it into |ExecutTranspose()| in "EditorCommand.cpp" to make |Editor|
class simpler for improving code health.

Following patch will expand |Transpose()| into |ExecutTranspose()|.

Bug: 672405
Change-Id: Icde253623f31813d2b4517c4da7d4798bd5fadf6
Reviewed-on: https://chromium-review.googlesource.com/583880
Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#489518}
static bool ExecuteYank(LocalFrame& frame,
                        Event*,
                        EditorCommandSource,
                        const String&) {
  const String& yank_string = frame.GetEditor().GetKillRing().Yank();
  if (DispatchBeforeInputInsertText(
          EventTargetNodeForDocument(frame.GetDocument()), yank_string,
          InputEvent::InputType::kInsertFromYank) !=
      DispatchEventResult::kNotCanceled)
    return true;

  if (frame.GetDocument()->GetFrame() != &frame)
    return false;

  frame.GetDocument()->UpdateStyleAndLayoutIgnorePendingStylesheets();

  frame.GetEditor().InsertTextWithoutSendingTextEvent(
      yank_string, false, 0, InputEvent::InputType::kInsertFromYank);
  frame.GetEditor().GetKillRing().SetToYankedState();
  return true;
}

static bool ExecuteYank(LocalFrame& frame,
                        Event*,
                        EditorCommandSource,
                        const String&) {
  const String& yank_string = frame.GetEditor().GetKillRing().Yank();
  if (DispatchBeforeInputInsertText(
          EventTargetNodeForDocument(frame.GetDocument()), yank_string,
          InputEvent::InputType::kInsertFromYank) !=
      DispatchEventResult::kNotCanceled)
    return true;

  if (frame.GetDocument()->GetFrame() != &frame)
    return false;

  frame.GetDocument()->UpdateStyleAndLayoutIgnorePendingStylesheets();

  frame.GetEditor().InsertTextWithoutSendingTextEvent(
      yank_string, false, 0, InputEvent::InputType::kInsertFromYank);
  frame.GetEditor().GetKillRing().SetToYankedState();
  return true;
}
