Remove always-on compositor capabilities

All context implementations the compositor uses support the following
capabilities:

- discard_backbuffer
- set_visibility
- map_sub
- shallow_flush

so there's no point in passing these values or, even worse, branching
on them.

R=piman

Review URL: https://codereview.chromium.org/94113004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239171 0039d316-1c4b-4281-b951-d872f2087c98
Settings: Do not call preventDefault() for a mousedown event targetting an edit-on-click control.

This CL fixes the following five bugs:

crbug.com/281239: 'Behavior' SELECT doesn't reset the value on canceling editing
crbug.com/306355: Text fields in lists don't getting dragged on the first click.
crbug.com/316527: 'Select all' context menu item on an editable text selects whole the page.
crbug.com/318688: Text drag&drop in a list removes the content of the source textfield.
crbug.com/324772: Touching a 'Behavior' column in content settings shows software keyboard.

There were two problems:

* If a mousedown event is kicked on an element representing static text version
  of an edit-on-click control, we called preventDefault() because there are no
  focusable elements between the element and the ListItem root.
  InlineEditableItem gives focus on the editable control in this case
  (editClickTarget_), but preventDefault() affected text drag and context menu
  unexpectedly.
  We need to avoid preventDefault() in this case. But this case was not
  detectable in handleMouseDown() in list.js. This CL makes the static text
  element focusable during mousedown processing, and move the focus to the
  editable control later.

* As for content settings, clicking on a staic text element in Behavior column
  gave focus on the first INPUT element in the ListItem, not the corresponding
  SELECT element.
  We should follow a way implemented in InlineEditableItem for this control
  too. We register pair of elements to InlineEditableItem::editFields_, and
  remove isExtraFocusableControl.

BUG=281239, 306355, 316527, 318688, 324772

Review URL: https://codereview.chromium.org/105733006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239172 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239172