Adds two new observer methods to allow code to be notified when a Window is added/removed from a ...

Adds two new observer methods to allow code to be notified when a Window is added/removed from a RootWindow. This allows hierarchy-specific cleanup code to execute when a Window is removed rather than when it is destroyed, necessary for multiple root windows.

http://crbug.com/112131
TEST=see unittests
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=119976

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=120025

[Ben Goodger (Google), 2012-01-31 22:16:01]

Currently we have code like this:

class Foo {
public:
  ~Foo() {
   
RootWindow::GetInstance()->GetCompositor()->DoSomethingRelatedTo(window_->layer());
  }
private:
  aura::Window* window_;
}

We need the code in the dtor to execute when window_ is detached from whatever
RootWindow it happens to be in. To do this we need a new detachment observer
notification.

[sky, 2012-01-31 22:20:58]

LGTM

http://codereview.chromium.org/9315015/diff/1/ui/aura/window.cc
File ui/aura/window.cc (right):

http://codereview.chromium.org/9315015/diff/1/ui/aura/window.cc#newcode647
ui/aura/window.cc:647: Window::Windows::const_iterator it = children_.begin();
nit: put iterator inside for loop here and 656.

[commit-bot: I haz the power, 2012-02-01 02:28:49]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ben@chromium.org/9315015/2003

[commit-bot: I haz the power, 2012-02-01 04:06:36]

Change committed as 120025