Remove attach/detach concept from InputType and InputTypeView.

- Rename InputTypeView::attach to startResourceLoading.
  It is used only for trigger image loading.
- Rename InputType::detach to closePopupView, and move it to InputTypeView.
  Make the name concrete, and it is definitely view-related.

BUG=306257
TEST=none; no behavior changes.

Review URL: https://codereview.chromium.org/63443004

git-svn-id: svn://svn.chromium.org/blink/trunk@162057 bbb929c8-8fbe-4397-9dbb-9b2b20218538