Make tab view order match tab strip model order

Bug: 897086
Change-Id: Idfd8e9a68c663ba3e560a6f2443b2a468cdd3c65
Reviewed-on: https://chromium-review.googlesource.com/c/1331617
Commit-Queue: Collin Baker <collinbaker@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608076}

chrome/browser/ui/views/tabs/tab_strip.cc

@@ -429,8 +429,14 @@ void TabStrip::StopAllHighlighting() {
 void TabStrip::AddTabAt(int model_index, TabRendererData data, bool is_active) {
   const bool was_single_tab_mode = SingleTabMode();
 
+  // Get view child index of where we want to insert
+  int view_index = 0;
+  if (model_index > 0) {
+    view_index = GetIndexOf(tab_at(model_index - 1)) + 1;
+  }
+
   Tab* tab = new Tab(this, animation_container_.get());
-  AddChildView(tab);
+  AddChildViewAt(tab, view_index);
   const bool pinned = data.pinned;
   tab->SetData(std::move(data));
   UpdateTabsClosingMap(model_index, 1);
@@ -487,8 +493,14 @@ void TabStrip::MoveTab(int from_model_index,
                        int to_model_index,
                        TabRendererData data) {
   DCHECK_GT(tabs_.view_size(), 0);
+
   const Tab* last_tab = GetLastVisibleTab();
   tab_at(from_model_index)->SetData(std::move(data));
+
+  // Keep child views in same order as tab strip model.
+  const int to_view_index = GetIndexOf(tab_at(to_model_index));
+  ReorderChildView(tab_at(from_model_index), to_view_index);
+
   if (touch_layout_) {
     tabs_.MoveViewOnly(from_model_index, to_model_index);
     int pinned_count = 0;

chrome/browser/ui/views/tabs/tab_strip_unittest.cc

@@ -311,6 +311,40 @@ TEST_P(TabStripTest, RemoveTab) {
   EXPECT_EQ(0, observer.last_tab_removed());
 }
 
+namespace {
+
+bool TabViewsInOrder(TabStrip* tab_strip) {
+  for (int i = 1; i < tab_strip->tab_count(); ++i) {
+    Tab* left = tab_strip->tab_at(i - 1);
+    Tab* right = tab_strip->tab_at(i);
+
+    if (tab_strip->GetIndexOf(right) < tab_strip->GetIndexOf(left)) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+}  // namespace
+
+// Verifies child view order matches model order.
+TEST_P(TabStripTest, TabViewOrder) {
+  controller_->AddTab(0, false);
+  controller_->AddTab(1, false);
+  controller_->AddTab(2, false);
+  EXPECT_TRUE(TabViewsInOrder(tab_strip_));
+
+  tab_strip_->MoveTab(0, 1, TabRendererData());
+  EXPECT_TRUE(TabViewsInOrder(tab_strip_));
+  tab_strip_->MoveTab(1, 2, TabRendererData());
+  EXPECT_TRUE(TabViewsInOrder(tab_strip_));
+  tab_strip_->MoveTab(1, 0, TabRendererData());
+  EXPECT_TRUE(TabViewsInOrder(tab_strip_));
+  tab_strip_->MoveTab(0, 2, TabRendererData());
+  EXPECT_TRUE(TabViewsInOrder(tab_strip_));
+}
+
 TEST_P(TabStripTest, VisibilityInOverflow) {
   constexpr int kInitialWidth = 250;
   tab_strip_->SetBounds(0, 0, kInitialWidth, 20);