Disallow toggling of shelf auto-hide with touch when there are no windows open

ash/shelf/shelf_layout_manager.cc

 // Copyright (c) 2012 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/shelf/shelf_layout_manager.h"
 
 #include <algorithm>
 #include <cmath>
 #include <vector>
 
@@ skipping 850 matching lines @@
   if (wm_shelf_->IsHorizontalAlignment())
     show_shelf_region_in_screen.set_height(kMaxAutoHideShowShelfRegionSize);
   else
     show_shelf_region_in_screen.set_width(kMaxAutoHideShowShelfRegionSize);
 
   // TODO: Figure out if we need any special handling when the keyboard is
   // visible.
   return show_shelf_region_in_screen;
 }
 
+bool ShelfLayoutManager::HasVisibleWindow() const {
+  const int64_t shelf_display_id =
+      WmWindow::Get(shelf_widget_->GetNativeWindow())
+          ->GetDisplayNearestWindow()
+          .id();
+  const std::vector<WmWindow*> windows =
+      Shell::Get()->mru_window_tracker()->BuildWindowListIgnoreModal();
+  // Process the window list and check if there are any visible windows.
+  // Ignore app list windows that may be animating to hide after dismissal.
+  bool visible_window = false;
+  for (size_t i = 0; i < windows.size(); ++i) {
+    if (windows[i] && windows[i]->IsVisible() && !IsAppListWindow(windows[i]) &&
+        !windows[i]->GetWindowState()->IsMinimized() &&
+        windows[i]->GetDisplayNearestWindow().id() == shelf_display_id) {
+      visible_window = true;

[xiaoyinh(OOO Sep 11-29), 2017/04/21 04:13:12]

nit: Just return true here, and return false at the end of the function.
visible_window won't be needed.

[minch1, 2017/04/21 16:42:42]

good point. Thanks.

+      break;
+    }
+  }
+  return visible_window;
+}
+
 ShelfAutoHideState ShelfLayoutManager::CalculateAutoHideState(
     ShelfVisibilityState visibility_state) const {
   if (visibility_state != SHELF_AUTO_HIDE || !wm_shelf_->IsShelfInitialized())
     return SHELF_AUTO_HIDE_HIDDEN;
 
   if (shelf_widget_->IsShowingAppList())
     return SHELF_AUTO_HIDE_SHOWN;
 
   if (shelf_widget_->status_area_widget() &&
       shelf_widget_->status_area_widget()->ShouldShowShelf())
     return SHELF_AUTO_HIDE_SHOWN;
 
   if (shelf_widget_->IsShowingContextMenu())
     return SHELF_AUTO_HIDE_SHOWN;
 
   if (shelf_widget_->IsShowingOverflowBubble())
     return SHELF_AUTO_HIDE_SHOWN;
 
   if (shelf_widget_->IsActive() ||
       (shelf_widget_->status_area_widget() &&
        shelf_widget_->status_area_widget()->IsActive()))
     return SHELF_AUTO_HIDE_SHOWN;
 
-  const int64_t shelf_display_id =
-      WmWindow::Get(shelf_widget_->GetNativeWindow())
-          ->GetDisplayNearestWindow()
-          .id();
-  const std::vector<WmWindow*> windows =
-      Shell::Get()->mru_window_tracker()->BuildWindowListIgnoreModal();
-  // Process the window list and check if there are any visible windows.
-  // Ignore app list windows that may be animating to hide after dismissal.
-  bool visible_window = false;
-  for (size_t i = 0; i < windows.size(); ++i) {
-    if (windows[i] && windows[i]->IsVisible() && !IsAppListWindow(windows[i]) &&
-        !windows[i]->GetWindowState()->IsMinimized() &&
-        windows[i]->GetDisplayNearestWindow().id() == shelf_display_id) {
-      visible_window = true;
-      break;
-    }
-  }
   // If there are no visible windows do not hide the shelf.
-  if (!visible_window)
+  if (!HasVisibleWindow())
     return SHELF_AUTO_HIDE_SHOWN;
 
   if (gesture_drag_status_ == GESTURE_DRAG_COMPLETE_IN_PROGRESS)
     return gesture_drag_auto_hide_state_;
 
   // Don't show if the user is dragging the mouse.
   if (in_mouse_drag_)
     return SHELF_AUTO_HIDE_HIDDEN;
 
   // Ignore the mouse position if mouse events are disabled.
@@ skipping 205 matching lines @@
           : SHELF_AUTO_HIDE_SHOWN;
   ShelfAutoHideBehavior new_auto_hide_behavior =
       gesture_drag_auto_hide_state_ == SHELF_AUTO_HIDE_SHOWN
           ? SHELF_AUTO_HIDE_BEHAVIOR_NEVER
           : SHELF_AUTO_HIDE_BEHAVIOR_ALWAYS;
 
   // When in fullscreen and the shelf is forced to be auto hidden, the auto hide
   // behavior affects neither the visibility state nor the auto hide state. Set
   // |gesture_drag_status_| to GESTURE_DRAG_COMPLETE_IN_PROGRESS to set the auto
   // hide state to |gesture_drag_auto_hide_state_|.
+  // Since the shelf will always be shown when there are no windows opend. There

[xiaoyinh(OOO Sep 11-29), 2017/04/21 04:13:12]

nit: s/opend/opened

+  // is no point to change the auto hide behavior when swiping down / up on the
+  // shelf.
   gesture_drag_status_ = GESTURE_DRAG_COMPLETE_IN_PROGRESS;
-  if (wm_shelf_->auto_hide_behavior() != new_auto_hide_behavior)
+  if (wm_shelf_->auto_hide_behavior() != new_auto_hide_behavior &&
+      HasVisibleWindow())
     wm_shelf_->SetAutoHideBehavior(new_auto_hide_behavior);
   else
     UpdateVisibilityState();
   gesture_drag_status_ = GESTURE_DRAG_NONE;
 }
 
 void ShelfLayoutManager::CancelGestureDrag() {
   gesture_drag_status_ = GESTURE_DRAG_CANCEL_IN_PROGRESS;
   UpdateVisibilityState();
   gesture_drag_status_ = GESTURE_DRAG_NONE;
 }
 
 }  // namespace ash