Add a NOT_DRAWN window in between the root_window and its children.

ash/wm/root_window_layout_manager.cc

Index: ash/wm/root_window_layout_manager.cc
diff --git a/ash/wm/root_window_layout_manager.cc b/ash/wm/root_window_layout_manager.cc
index aa7301dd06d485d8d2cf4afb2c37114d9f47cc09..40b4df66b004c665e64f86603a9b06b1de9dfae5 100644
--- a/ash/wm/root_window_layout_manager.cc
+++ b/ash/wm/root_window_layout_manager.cc
@@ -9,6 +9,34 @@
 #include "ui/aura/window_tracker.h"
 
 namespace ash {
+
+namespace {
+
+// Resize all container windows that RootWindowLayoutManager is responsible for.
+// That includes all container windows up to three depth except that top level
+// window which has a delegate. We cannot simply check top level window, because
+// we need to skip other windows without a delegate, such as ScreenDimmer
+// windows.
+// TODO(wutao): The above logic is error prone. Consider using a Shell window id
+// to indentify such a container.
+void ResizeWindow(const aura::Window::Windows& children,
+                  const gfx::Rect& fullscreen_bounds,
+                  int depth) {
+  if (depth > 2)
+    return;
+  const int child_depth = depth + 1;
+  aura::WindowTracker children_tracker(children);
+  while (!children_tracker.windows().empty()) {
+    aura::Window* child = children_tracker.Pop();
+    if (child->GetToplevelWindow())
+      continue;
+    child->SetBounds(fullscreen_bounds);
+    ResizeWindow(child->children(), fullscreen_bounds, child_depth);
+  }
+}
+
+}  // namespace
+
 namespace wm {
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -23,26 +51,8 @@ RootWindowLayoutManager::~RootWindowLayoutManager() {}
 // RootWindowLayoutManager, aura::LayoutManager implementation:
 
 void RootWindowLayoutManager::OnWindowResized() {
-  const gfx::Rect fullscreen_bounds = gfx::Rect(owner_->GetBounds().size());
-
-  // Resize both our immediate children (the containers-of-containers animated
-  // by PowerButtonController) and their children (the actual containers).
-  aura::WindowTracker children_tracker(owner_->aura_window()->children());
-  while (!children_tracker.windows().empty()) {
-    aura::Window* child = children_tracker.Pop();
-    // Skip descendants of top-level windows, i.e. only resize containers and
-    // other windows without a delegate, such as ScreenDimmer windows.
-    if (child->GetToplevelWindow())
-      continue;
-
-    child->SetBounds(fullscreen_bounds);
-    aura::WindowTracker grandchildren_tracker(child->children());
-    while (!grandchildren_tracker.windows().empty()) {
-      child = grandchildren_tracker.Pop();
-      if (!child->GetToplevelWindow())
-        child->SetBounds(fullscreen_bounds);
-    }
-  }
+  ResizeWindow(owner_->aura_window()->children(),
+               gfx::Rect(owner_->GetBounds().size()), 0);
 }
 
 void RootWindowLayoutManager::OnWindowAddedToLayout(WmWindow* child) {}