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

ash/shelf/shelf_layout_manager.cc

Index: ash/shelf/shelf_layout_manager.cc
diff --git a/ash/shelf/shelf_layout_manager.cc b/ash/shelf/shelf_layout_manager.cc
index a054cc94e6ff9297d5b94c429d4f80cc458062f9..0f1ec6871549ec61403dfc434544e7b26d460bba 100644
--- a/ash/shelf/shelf_layout_manager.cc
+++ b/ash/shelf/shelf_layout_manager.cc
@@ -868,6 +868,27 @@ gfx::Rect ShelfLayoutManager::GetAutoHideShowShelfRegionInScreen() const {
   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())
@@ -891,25 +912,8 @@ ShelfAutoHideState ShelfLayoutManager::CalculateAutoHideState(
        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)
@@ -1135,8 +1139,12 @@ void ShelfLayoutManager::CompleteGestureDrag(const ui::GestureEvent& gesture) {
   // 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();