Makes View::focusable() return last value supplied to SetFocusable()

Makes View::focusable() return last value supplied to SetFocusable()

As focusable() may effect the preferred size it is important that it
returns the last value passed to SetFocusable() rather than if the
view is focusable right now. Otherwise focusable() could change value
based on enabled or visible state, resulting in the preferred size
bouncing around.

I'm also making focusable() protected as it's really only subclasses
that should care about it. Especially since we also have
IsFocusable().

BUG=330696
TEST=covered by test
R=ben@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=244282

[Ben Goodger (Google), 2014-01-09 04:13:03]

lgtm

[commit-bot: I haz the power, 2014-01-09 15:44:01]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/sky@chromium.org/129863002/200001

[commit-bot: I haz the power, 2014-01-09 17:01:10]

Retried try job too often on win_rel for step(s) browser_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_rel&nu...

[commit-bot: I haz the power, 2014-01-10 18:49:14]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/sky@chromium.org/129863002/200001

[commit-bot: I haz the power, 2014-01-10 23:24:57]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/sky@chromium.org/129863002/200001

[commit-bot: I haz the power, 2014-01-11 00:13:26]

Change committed as 244282