Added common layout framework for system menu rows.

ui/views/view.cc

Index: ui/views/view.cc
diff --git a/ui/views/view.cc b/ui/views/view.cc
index 3cb42dca9dab0b6b57422f07348b4cc15293f3fa..d5da6b5b07f827138f42f7776b2f301d3001f928 100644
--- a/ui/views/view.cc
+++ b/ui/views/view.cc
@@ -128,6 +128,10 @@ View::~View() {
 
   ViewStorage::GetInstance()->ViewRemoved(this);
 
+  // Some layout managers hold a reference to the host that they are installed

[sky, 2016/10/20 15:59:11]

I have a mild preference to move this after deleting the children. That's what
we do in ~Window. Does that work for your case?

[bruthig, 2016/10/20 19:01:34]

The risk in doing so is that View may try to access a deleted child but I was
able to include a test to guard against this so I've changed it as requested.

[sky, 2016/10/20 20:42:22]

Now that I look at this code again I think the way you had it is better, because
apparently we won't call LayoutManager::ViewRemoved() because of the parent =
NULL below. So, I think either move the reset where you had it, or make
ViewRemoved be called. Sorry for the run around.

[bruthig, 2016/10/20 21:00:48]

Done.

+  // to and may need to access this during destruction.
+  layout_manager_.reset();
+
   for (Views::const_iterator i(children_.begin()); i != children_.end(); ++i) {
     (*i)->parent_ = NULL;
     if (!(*i)->owned_by_client_)