[multipaste] Remember old MenuPosition

To prevent multipaste from jumping when deleting items,
remember the old menu position.

Bug: 1165288
Change-Id: I136d43ec9524a6ddcaff1ba371a50e90ce321d0a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2633963
Commit-Queue: Alex Newcomer <newcomer@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844314}

ui/views/controls/menu/menu_controller.cc

@@ -2481,14 +2481,33 @@ gfx::Rect MenuController::CalculateBubbleMenuBounds(MenuItemView* item,
           item->set_actual_menu_position(MenuPosition::kBelowBounds);
         }
       } else if (state_.anchor == MenuAnchorPosition::kBubbleBelow) {
-        y = y_for_menu_below;
-        item->set_actual_menu_position(MenuPosition::kBelowBounds);
-        if (y + menu_size.height() > monitor_bounds.bottom()) {
+        // Respect the previous MenuPosition. The menu contents could change
+        // while the menu is shown, the menu position should not change.
+        const bool able_to_show_menu_below =
+            (y_for_menu_below + menu_size.height() <= monitor_bounds.bottom());
+        const bool able_to_show_menu_above =
+            y_for_menu_above >= monitor_bounds.y();
+        if (item->actual_menu_position() == MenuPosition::kBelowBounds &&
+            able_to_show_menu_below) {
+          y = y_for_menu_below;
+        } else if (item->actual_menu_position() == MenuPosition::kAboveBounds &&
+                   able_to_show_menu_above) {
+          y = y_for_menu_above;
+        } else if (able_to_show_menu_below) {
+          y = y_for_menu_below;
+          item->set_actual_menu_position(MenuPosition::kBelowBounds);
+        } else if (able_to_show_menu_above) {
+          // No room below, but there is room above. Show above the anchor.
+          // Align the bottom of the menu with the bottom of the anchor.
           y = y_for_menu_above;
           item->set_actual_menu_position(MenuPosition::kAboveBounds);
+        } else {
+          // No room above or below. Show as low as possible. Align the bottom
+          // of the menu with the bottom of the screen.
+          y = monitor_bounds.bottom() - menu_size.height();
+          item->set_actual_menu_position(MenuPosition::kBestFit);
         }
       }
-
     } else if (state_.anchor == MenuAnchorPosition::kBubbleLeft ||
                state_.anchor == MenuAnchorPosition::kBubbleRight) {
       if (state_.anchor == MenuAnchorPosition::kBubbleLeft) {

ui/views/controls/menu/menu_controller_unittest.cc

@@ -1063,6 +1063,70 @@ TEST_F(MenuControllerTest, VerifyMenuBubblePositionAfterSizeChanges) {
   }
 }
 
+// Verifies that the context menu bubble position, MenuPosition::kBubbleBelow,
+// does not shift as items are removed. The menu position will shift it items
+// are added and the menu no longer fits in its previous position.
+TEST_F(MenuControllerTest, VerifyMenuBubbleBelowPositionAfterSizeChanges) {
+  constexpr gfx::Rect kMonitorBounds(0, 0, 500, 500);
+  constexpr gfx::Size kMenuSize(100, 200);
+  const gfx::Insets border_and_shadow_insets =
+      BubbleBorder::GetBorderAndShadowInsets(
+          MenuConfig::instance().touchable_menu_shadow_elevation);
+
+  // Calculate the suitable anchor point to ensure that if the menu shows below
+  // the anchor point, the bottom of the menu should be one pixel off the
+  // bottom of the display. It means that there is insufficient space for the
+  // menu below the anchor.
+  const gfx::Point anchor_point(kMonitorBounds.width() / 2,
+                                kMonitorBounds.bottom() + 1 -
+                                    kMenuSize.height() +
+                                    border_and_shadow_insets.top());
+
+  MenuBoundsOptions options;
+  options.menu_anchor = MenuAnchorPosition::kBubbleBelow;
+  options.monitor_bounds = kMonitorBounds;
+  options.anchor_bounds = gfx::Rect(anchor_point, gfx::Size());
+
+  // Case 1: There is insufficient space for the menu below `anchor_point` and
+  // there is no cached menu position. The menu should show above the anchor.
+  {
+    options.menu_size = kMenuSize;
+    ASSERT_GT(options.anchor_bounds.y() - border_and_shadow_insets.top() +
+                  kMenuSize.height(),
+              kMonitorBounds.bottom());
+    CalculateBubbleMenuBounds(options);
+    EXPECT_EQ(MenuItemView::MenuPosition::kAboveBounds,
+              menu_item()->ActualMenuPosition());
+  }
+
+  // Case 2: There is insufficient space for the menu below `anchor_point`. The
+  // cached position is below the anchor. The menu should show above the anchor
+  // point.
+  {
+    options.menu_position = MenuItemView::MenuPosition::kBelowBounds;
+    CalculateBubbleMenuBounds(options);
+    EXPECT_EQ(MenuItemView::MenuPosition::kAboveBounds,
+              menu_item()->ActualMenuPosition());
+  }
+
+  // Case 3: There is enough space for the menu below `anchor_point`. The cached
+  // menu position is above the anchor. The menu should show above the anchor.
+  {
+    // Shrink the menu size. Verify that there is enough space below the anchor
+    // point now.
+    constexpr gfx::Size kUpdatedSize(kMenuSize.width(), kMenuSize.height() / 2);
+    options.menu_size = kUpdatedSize;
+    EXPECT_LE(options.anchor_bounds.y() - border_and_shadow_insets.top() +
+                  kUpdatedSize.height(),
+              kMonitorBounds.bottom());
+
+    options.menu_position = MenuItemView::MenuPosition::kAboveBounds;
+    CalculateBubbleMenuBounds(options);
+    EXPECT_EQ(MenuItemView::MenuPosition::kAboveBounds,
+              menu_item()->ActualMenuPosition());
+  }
+}
+
 // Tests that opening the menu and pressing 'Home' selects the first menu item.
 TEST_F(MenuControllerTest, FirstSelectedItem) {
   SetPendingStateItem(menu_item()->GetSubmenu()->GetMenuItemAt(0));