Defer preparing for overview until all overview items are initialized.

Defer preparing for overview until all overview items are initialized.

BUG=384495
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=281918

[flackr, 2014-07-02 22:35:20]

I'm not sure why I haven't been able to reproduce this (manually or in a test)
but the crash seems to be that we've observed a bounds change on a window that's
not yet in the window_list_. PrepareForOverview restores minimized windows which
can cause the window to move in which case it will try to find the current
window in the list (which silently fails the DCHECK in
WindowGrid::OnWindowBoundsChanged and tries to call RecomputeWindowTransforms on
an uninitialized item). WDYT?

[Nina, 2014-07-03 14:56:06]

LGTM, a pity we can't reproduce it.

[oshima, 2014-07-08 20:39:07]

lgtm

This seems to happen when

1) there is a minimized window that
  a) is nearly outside of the work area, or
  b) is auto positioned (new window that are not moved by a user)
2) and layer skipped set bounds animation.

Couldn't figure out how/when 2) can happen. vollic@ may know?

[flackr, 2014-07-08 20:41:35]

The CQ bit was checked by flackr@chromium.org

[commit-bot: I haz the power, 2014-07-08 20:43:54]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/flackr@chromium.org/363133002/1

[commit-bot: I haz the power, 2014-07-09 04:06:45]

Change committed as 281918