Register the window in MaximizeModeWindowManager when the window is shown.

ash/common/wm/maximize_mode/maximize_mode_window_manager.cc

Index: ash/common/wm/maximize_mode/maximize_mode_window_manager.cc
diff --git a/ash/common/wm/maximize_mode/maximize_mode_window_manager.cc b/ash/common/wm/maximize_mode/maximize_mode_window_manager.cc
index 3d0ea92f86cd16b0851dfe9ccc992063b9df4116..63c8715a6a52bfb25e4c19f79efc7e2b9ab2eacc 100644
--- a/ash/common/wm/maximize_mode/maximize_mode_window_manager.cc
+++ b/ash/common/wm/maximize_mode/maximize_mode_window_manager.cc
@@ -99,6 +99,10 @@ void MaximizeModeWindowManager::OnWindowDestroying(WmWindow* window) {
     // container window can be removed on display destruction.
     window->RemoveObserver(this);
     observed_container_windows_.erase(window);
+  } else if (base::ContainsValue(added_windows_, window)) {
+    // Added window was destroyed before being shown.
+    added_windows_.erase(window);
+    window->RemoveObserver(this);
   } else {
     // If a known window gets destroyed we need to remove all knowledge about
     // it.
@@ -112,6 +116,15 @@ void MaximizeModeWindowManager::OnWindowTreeChanged(
   // A window can get removed and then re-added by a drag and drop operation.
   if (params.new_parent && IsContainerWindow(params.new_parent) &&
       !base::ContainsKey(window_state_map_, params.target)) {
+    // Wait until the window become visible because the client
+    // may update the flag to control if the window should be added.
+    if (!params.target->IsVisible()) {

[Mr4D (OOO till 08-26), 2016/08/18 01:45:45]

This is confusing. You mention "wait until the window becomes visible" but then
if (!...isVisible()).

Maybe you should write:
If the window is invisible we do .. since the client may update ..?

[oshima, 2016/08/18 04:26:09]

Updated to:

    // Don't register the window if the window is invisible. Instead,
    // wait until it becomes visible because the client may update the
    // flag to control if the window should be added.

+      if (!base::ContainsValue(added_windows_, params.target)) {
+        added_windows_.insert(params.target);
+        params.target->AddObserver(this);
+      }
+      return;
+    }
     MaximizeAndTrackWindow(params.target);
     // When the state got added, the "WM_EVENT_ADDED_TO_WORKSPACE" event got
     // already sent and we have to notify our state again.
@@ -141,6 +154,26 @@ void MaximizeModeWindowManager::OnWindowBoundsChanged(
     pair.second->UpdateWindowPosition(pair.first->GetWindowState());
 }
 
+void MaximizeModeWindowManager::OnWindowVisibilityChanged(WmWindow* window,
+                                                          bool visible) {
+  // Skip if it's already managed.
+  if (base::ContainsKey(window_state_map_, window))
+    return;
+
+  if (IsContainerWindow(window->GetParent()) &&
+      base::ContainsValue(added_windows_, window) && visible) {
+    added_windows_.erase(window);
+    window->RemoveObserver(this);
+    MaximizeAndTrackWindow(window);
+    // When the state got added, the "WM_EVENT_ADDED_TO_WORKSPACE" event got
+    // already sent and we have to notify our state again.
+    if (base::ContainsKey(window_state_map_, window)) {
+      wm::WMEvent event(wm::WM_EVENT_ADDED_TO_WORKSPACE);
+      window->GetWindowState()->OnWMEvent(&event);
+    }

[Mr4D (OOO till 08-26), 2016/08/18 01:45:45]

Could you put line 167-173 into a function and call that from here and from line
128?

[oshima, 2016/08/18 04:26:09]

I believe we can move the added to workspace to MaximizeAndTrackWindow, but let
me do it in a separate CL because this has to be merged to m53.

+  }
+}
+
 void MaximizeModeWindowManager::OnDisplayAdded(
     const display::Display& display) {
   DisplayConfigurationChanged();