Changes container names and adds a couple of more

mash/wm/public/interfaces/container.mojom

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 module mash.wm.mojom;
 
 // Containers for windows. This list is in the z-order of the windows, however
-// they are actually built in a hierarchy (e.g. USER_WORKSPACE and LOGIN_WINDOWS
-// are siblings). See RootWindowController::CreateContainers() for the full
-// hierarchy. 
+// they are actually built in a hierarchy (e.g. USER_CONTAINER and
+// LOGIN_CONTAINER are siblings). See RootWindowController::CreateContainers()
+// for the full hierarchy.
+//
+// NOTE: containers ending with '_CONTAINER' exist purely to hold other
+// Containers. Containers whose name starts with an earlier name are children.
+// For example, USER_BACKGROUND is a child of USER_CONTAINER and
+// USER_PRIVATE_WINDOWS is a child of USER_PRIVATE_CONTAINER.
 enum Container {
-  ROOT = 0,
+  ROOT_CONTAINER = 0,
   ALL_USER_BACKGROUND,
-  USER_WORKSPACE,
+  USER_CONTAINER,
   USER_BACKGROUND,
-  USER_PRIVATE,
-  USER_WINDOWS,
-  USER_ALWAYS_ON_TOP_WINDOWS,
-  USER_PRESENTATION_WINDOWS,
-  USER_SHELF,
+  // Container that is hidden when screen is locked, child of USER_CONTAINER.
+  USER_PRIVATE_CONTAINER,

[James Cook, 2016/05/13 17:14:44]

I think it would be just as clear to use a short name for the parent container
and longer names for children, e.g.

USER_PRIVATE
USER_PRIVATE_WINDOWS
USER_PRIVATE_ALWAYS_ON_TOP_WINDOWS

Then you don't have the situation that they are all containers, but some have
_CONTAINER in the name.

If you really think it needs something to indicate that it's a container of
containers, maybe USER_PRIVATE_PARENT? USER_PRIVATE_ROOT?

[sky, 2016/05/13 19:14:06]

Done.

+  USER_PRIVATE_WINDOWS,
+  USER_PRIVATE_ALWAYS_ON_TOP_WINDOWS,
+  USER_PRIVATE_DOCKED_WINDOWS,
+  USER_PRIVATE_PRESENTATION_WINDOWS,
+  USER_PRIVATE_SHELF,
+  USER_PRIVATE_PANELS,
+  USER_PRIVATE_APP_LIST,
+  USER_PRIVATE_SYSTEM_MODAL,
+  LOGIN_CONTAINER,

[James Cook, 2016/05/13 17:14:44]

optional: This file might be clearer with a blank line between each "section" of
containers, like here.

[sky, 2016/05/13 19:14:06]

I couldn't come up with a sensical way to add whitespace to this file, so I'm
sticking with no whitespace.

   LOGIN_WINDOWS,
   LOGIN_APP,    // TODO(beng): what about dialog boxes login opens?
   LOGIN_SHELF,
   // Status area widget and message center notification popups.
   STATUS,
   // Bubble windows, for example the sysui system tray bubble and the screen
   // brightness bubble.
   BUBBLES,
   SYSTEM_MODAL_WINDOWS,
   KEYBOARD,
   MENUS,
-  TOOLTIPS,
+  DRAG_AND_TOOLTIPS,
   COUNT
 };
 
 const string kWindowContainer_Property = "ash:window-container";