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

ash/common/wm/root_window_layout_manager.cc

Index: ash/common/wm/root_window_layout_manager.cc
diff --git a/ash/common/wm/root_window_layout_manager.cc b/ash/common/wm/root_window_layout_manager.cc
index 15ec3fbfaaa0219b4aa5d078c9da5d5a12fa3be3..77ba63c45cf7c5da3c23b3c9c88c23bf99ba870e 100644
--- a/ash/common/wm/root_window_layout_manager.cc
+++ b/ash/common/wm/root_window_layout_manager.cc
@@ -9,6 +9,28 @@
 #include "ui/aura/window_tracker.h"
 
 namespace ash {
+
+namespace {
+
+void ResizeWindow(const aura::Window::Windows& children,
+                  const gfx::Rect& fullscreen_bounds) {
+  // Resize both our immediate children (the containers-of-containers animated
+  // by PowerButtonController) and their children (the actual containers).
+  aura::WindowTracker children_tracker(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);
+    ResizeWindow(child->children(), fullscreen_bounds);

[oshima, 2017/04/05 20:26:51]

I don't think this is right. There may be non top level window that shouldn't be
changed. Tooltip is one of such examples, but there will be more.

[wutao, 2017/04/05 23:37:34]

I will add a third parameter |depth| and return if it is more than 3 layers.

+  }
+}
+
+}  // namespace
+
 namespace wm {
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -23,26 +45,8 @@ 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()));
 }
 
 void RootWindowLayoutManager::OnWindowAddedToLayout(WmWindow* child) {}