Do not show the auto-hide shelf if there is a single PIP window.

Bug: 942991
Test: unit test
Change-Id: Id1956d3fe239c0740770274a95ba9119f6fe2bc9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1529500Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Commit-Queue: Eliot Courtney <edcourtney@chromium.org>
Cr-Commit-Position: refs/heads/master@{#642375}

ash/shelf/shelf_layout_manager.cc

@@ -1122,7 +1122,10 @@ bool ShelfLayoutManager::HasVisibleWindow() const {
       return true;
     }
   }
-  return false;
+  auto* pip_container = Shell::GetContainer(root, kShellWindowId_PipContainer);
+  // The PIP window is not activatable and is not in the MRU list, but count
+  // it as a visible window for shelf auto-hide purposes. See crbug.com/942991.
+  return !pip_container->children().empty();
 }
 
 ShelfAutoHideState ShelfLayoutManager::CalculateAutoHideState(

ash/shelf/shelf_layout_manager_unittest.cc

@@ -2763,6 +2763,28 @@ TEST_F(ShelfLayoutManagerTest, A11yAlertOnWorkspaceState) {
             client.last_a11y_alert());
 }
 
+// Verifies the auto-hide shelf is hidden if there is only a single PIP window.
+TEST_F(ShelfLayoutManagerTest, AutoHideShelfHiddenForSinglePipWindow) {
+  Shelf* shelf = GetPrimaryShelf();
+  shelf->SetAutoHideBehavior(SHELF_AUTO_HIDE_BEHAVIOR_ALWAYS);
+  EXPECT_EQ(SHELF_AUTO_HIDE, shelf->GetVisibilityState());
+  EXPECT_EQ(SHELF_AUTO_HIDE_SHOWN, shelf->GetAutoHideState());
+
+  // Create a PIP window.
+  aura::Window* window = CreateTestWindow();
+  window->SetBounds(gfx::Rect(0, 0, 100, 100));
+  // Set always on top so it is put in the PIP container.
+  window->SetProperty(aura::client::kAlwaysOnTopKey, true);
+  window->Show();
+  const wm::WMEvent pip_event(wm::WM_EVENT_PIP);
+  wm::GetWindowState(window)->OnWMEvent(&pip_event);
+  Shell::Get()->UpdateShelfVisibility();
+
+  // Expect the shelf to be hidden.
+  EXPECT_EQ(SHELF_AUTO_HIDE, shelf->GetVisibilityState());
+  EXPECT_EQ(SHELF_AUTO_HIDE_HIDDEN, shelf->GetAutoHideState());
+}
+
 class ShelfLayoutManagerKeyboardTest : public AshTestBase {
  public:
   ShelfLayoutManagerKeyboardTest() = default;