Prevent taps from suppressing selection handle updates

A recent change made selection handle activation more strict, preventing
tap gestures from showing the handles. This inadvertently caused an
issue where tapping during a selection would prevent subsequent
selection handle updates. Fix this by only suppressing selection handle
activation after a tap if there's no active selection.

BUG=486045

Review URL: https://codereview.chromium.org/1135813002

Cr-Commit-Position: refs/heads/master@{#328995}

ui/touch_selection/touch_selection_controller.cc

@@ -79,6 +79,8 @@ void TouchSelectionController::OnSelectionBoundsChanged(
 
   if (!activate_selection_automatically_ &&
       !activate_insertion_automatically_) {
+    DCHECK(!is_insertion_active_);
+    DCHECK(!is_selection_active_);
     DCHECK_EQ(INPUT_EVENT_TYPE_NONE, response_pending_input_event_);
     return;
   }
@@ -173,7 +175,8 @@ void TouchSelectionController::AllowShowingFromCurrentSelection() {
 
 void TouchSelectionController::OnTapEvent() {
   response_pending_input_event_ = TAP;
-  activate_selection_automatically_ = false;
+  if (!is_selection_active_)
+    activate_selection_automatically_ = false;
   ShowInsertionHandleAutomatically();
   if (selection_empty_ && !show_on_tap_for_empty_editable_)
     DeactivateInsertion();

ui/touch_selection/touch_selection_controller_unittest.cc

@@ -924,6 +924,14 @@ TEST_F(TouchSelectionControllerTest, NoSelectionAfterLongpressThenTap) {
   controller().OnLongPressEvent();
   ChangeSelection(start_rect, visible, end_rect, visible);
   EXPECT_THAT(GetAndResetEvents(), ElementsAre(SELECTION_SHOWN));
+
+  // Tapping again shouldn't have any effect on subsequent selection events.
+  controller().OnTapEvent();
+  end_rect.Offset(10, 10);
+  ChangeSelection(start_rect, visible, end_rect, visible);
+  EXPECT_THAT(GetAndResetEvents(), ElementsAre(SELECTION_MOVED));
+  ClearSelection();
+  EXPECT_THAT(GetAndResetEvents(), ElementsAre(SELECTION_CLEARED));
 }
 
 TEST_F(TouchSelectionControllerTest, AllowShowingFromCurrentSelection) {