[ash-md] Prevents auto-positioning after cancelling overview

ash/common/wm/overview/window_selector.cc

 // Copyright 2013 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.
 
 #include "ash/common/wm/overview/window_selector.h"
 
 #include <algorithm>
 #include <functional>
 #include <set>
 #include <utility>
@@ skipping 267 matching lines @@
       restore_focus_window_(WmShell::Get()->GetFocusedWindow()),
       ignore_activations_(false),
       selected_grid_index_(0),
       overview_start_time_(base::Time::Now()),
       num_key_presses_(0),
       num_items_(0),
       showing_selection_widget_(false),
       text_filter_string_length_(0),
       num_times_textfield_cleared_(0),
       restoring_minimized_windows_(false),
-      text_filter_bottom_(0) {
+      text_filter_bottom_(0),
+      shutting_down_(false) {
   DCHECK(delegate_);
 }
 
 WindowSelector::~WindowSelector() {
   RemoveAllObservers();
 }
 
 // NOTE: The work done in Init() is not done in the constructor because it may
 // cause other, unrelated classes, (ie PanelLayoutManager) to make indirect
 // calls to restoring_minimized_windows() on a partially constructed object.
@@ skipping 75 matching lines @@
   WmShell::Get()->accessibility_delegate()->TriggerAccessibilityAlert(
       A11Y_ALERT_WINDOW_OVERVIEW_MODE_ENTERED);
 
   UpdateShelfVisibility();
 }
 
 // NOTE: The work done in Shutdown() is not done in the destructor because it
 // may cause other, unrelated classes, (ie PanelLayoutManager) to make indirect
 // calls to restoring_minimized_windows() on a partially destructed object.
 void WindowSelector::Shutdown() {
+  shutting_down_ = true;

[oshima, 2016/08/08 22:47:37]

can we just remove observer?

[varkha, 2016/08/08 23:45:35]

Yes, I considered this before but thought for some reason that we DCHECK on
repeated removal but we don't, at least not implicitly.
Done.

   size_t remaining_items = 0;
   for (std::unique_ptr<WindowGrid>& window_grid : grid_list_) {
     for (WindowSelectorItem* window_selector_item : window_grid->window_list())
       window_selector_item->RestoreWindow();
     remaining_items += window_grid->size();
   }
 
   // Setting focus after restoring windows' state avoids unnecessary animations.
   ResetFocusRestoreWindow(true);
   RemoveAllObservers();
@@ skipping 152 matching lines @@
 
 void WindowSelector::OnDisplayAdded(const display::Display& display) {}
 
 void WindowSelector::OnDisplayRemoved(const display::Display& display) {
   // TODO(flackr): Keep window selection active on remaining displays.
   CancelSelection();
 }
 
 void WindowSelector::OnDisplayMetricsChanged(const display::Display& display,
                                              uint32_t metrics) {
-  // If only the work area changes, there is no need to reposition windows in
-  // overview.
-  if (metrics != DISPLAY_METRIC_WORK_AREA) {
-    PositionWindows(/* animate */ false);
-    RepositionTextFilterOnDisplayMetricsChange();
-  }
+  if (shutting_down_)
+    return;
+  PositionWindows(/* animate */ false);
+  RepositionTextFilterOnDisplayMetricsChange();
 }
 
 void WindowSelector::OnWindowTreeChanged(WmWindow* window,
                                          const TreeChangeParams& params) {
   // Only care about newly added children of |observed_windows_|.
   if (!observed_windows_.count(window) ||
       !observed_windows_.count(params.new_parent)) {
     return;
   }
 
@@ skipping 141 matching lines @@
   for (size_t i = 0; i <= grid_list_.size() &&
                      grid_list_[selected_grid_index_]->Move(direction, animate);
        i++) {
     selected_grid_index_ =
         (selected_grid_index_ + display_direction + grid_list_.size()) %
         grid_list_.size();
   }
 }
 
 }  // namespace ash