Don't minimize dragged window when shelf hidden.

If the shelf hides we should not immediately minimize a dragged panel. This panel can be dropped where it now is and detached.

BUG=393047
TEST=PanelWindowResizerTest.DetachThenHideShelf
TEST=Drag a panel window while switching profiles. There is no crash and the window is detached where it was when switching back.

Review URL: https://codereview.chromium.org/582803002

Cr-Commit-Position: refs/heads/master@{#295711}

ash/wm/panels/panel_layout_manager.cc

@@ -551,10 +551,14 @@ void PanelLayoutManager::WillChangeVisibilityState(
     return;
   scoped_ptr<aura::WindowTracker> minimized_windows(new aura::WindowTracker);
   for (PanelList::iterator iter = panel_windows_.begin();
-       iter != panel_windows_.end(); ++iter) {
-    if (iter->window->IsVisible()) {
-      minimized_windows->Add(iter->window);
-      wm::GetWindowState(iter->window)->Minimize();
+       iter != panel_windows_.end();) {
+    aura::Window* window = iter->window;
+    // Minimizing a panel window may remove it from the panel_windows_ list.
+    // Advance the iterator before minimizing it: http://crbug.com/393047.
+    ++iter;
+    if (window != dragged_panel_ && window->IsVisible()) {
+      minimized_windows->Add(window);
+      wm::GetWindowState(window)->Minimize();
     }
   }
   restore_windows_on_shelf_visible_ = minimized_windows.Pass();

ash/wm/panels/panel_window_resizer_unittest.cc

@@ -273,6 +273,38 @@ TEST_F(PanelWindowResizerTest, PanelDetachReattachTop) {
   DetachReattachTest(window.get(), 0, 1);
 }
 
+// Tests that a drag continues when the shelf is hidden. This occurs as part of
+// the animation when switching profiles. http://crbug.com/393047.
+TEST_F(PanelWindowResizerTest, DetachThenHideShelf) {
+  if (!SupportsHostWindowResize())
+    return;
+  scoped_ptr<aura::Window> window(
+      CreatePanelWindow(gfx::Point(0, 0)));
+  wm::WindowState* state = wm::GetWindowState(window.get());
+  gfx::Rect expected_bounds = window->GetBoundsInScreen();
+  expected_bounds.set_y(expected_bounds.y() - 100);
+  DragStart(window.get());
+  DragMove(0, -100);
+  EXPECT_FALSE(state->IsMinimized());
+
+  // Hide the shelf. This minimizes all attached windows but should ignore
+  // the dragged window.
+  ShelfLayoutManager* shelf = RootWindowController::ForWindow(window.get())->
+      shelf()->shelf_layout_manager();
+  shelf->SetAutoHideBehavior(SHELF_AUTO_HIDE_ALWAYS_HIDDEN);
+  shelf->UpdateVisibilityState();
+  RunAllPendingInMessageLoop();
+  EXPECT_FALSE(state->IsMinimized());
+  EXPECT_EQ(kShellWindowId_PanelContainer, window->parent()->id());
+  DragEnd();
+
+  // When the drag ends the window should be detached and placed where it was
+  // dragged to.
+  EXPECT_EQ(kShellWindowId_DefaultContainer, window->parent()->id());
+  EXPECT_FALSE(state->IsMinimized());
+  EXPECT_EQ(expected_bounds.ToString(), window->GetBoundsInScreen().ToString());
+}
+
 TEST_F(PanelWindowResizerTest, PanelDetachReattachMultipleDisplays) {
   if (!SupportsMultipleDisplays())
     return;