Select the undo closure tab for conditional tab strip

Bug: 1078169
Change-Id: I62bd049309a19ef41bb503fcaff8e1c7ed998847
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2225533Reviewed-by: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Commit-Queue: Yue Zhang <yuezhanggg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#774378}

chrome/android/features/tab_ui/java/src/org/chromium/chrome/browser/tasks/tab_management/TabListMediator.java

@@ -471,6 +471,12 @@ class TabListMediator {
             @Override
             public void tabClosureUndone(Tab tab) {
                 onTabAdded(tab, !mActionsOnAllRelatedTabs);
+                if (TabUiFeatureUtilities.isConditionalTabStripEnabled()) {
+                    mTabModelSelector.getCurrentModel().setIndex(
+                            TabModelUtils.getTabIndexById(
+                                    mTabModelSelector.getCurrentModel(), tab.getId()),
+                            TabSelectionType.FROM_USER);
+                }
                 if (sTabClosedFromMapTabClosedFromMap.containsKey(tab.getId())) {
                     @TabClosedFrom
                     int from = sTabClosedFromMapTabClosedFromMap.get(tab.getId());

chrome/android/features/tab_ui/javatests/src/org/chromium/chrome/browser/tasks/tab_management/ConditionalTabStripTest.java

@@ -323,17 +323,18 @@ public class ConditionalTabStripTest {
         verifyShowingStrip(cta, false, 2);
         verifyStripSelectedPosition(cta, 1);
 
-        // Click the selected item to close the second-to-last tab, and the strip should be hidden
+        // Click the selected item to close the last tab, and the strip should be hidden
         // after closure.
         clickNthItemInStrip(1);
         verifyHidingStrip();
         verifyTabModelTabCount(cta, 1, 0);
 
-        // Click undo to bring back the second-to-last tab, and should bring back the tab strip as
-        // well.
+        // Click undo to bring back the last tab, and should bring back the tab strip as
+        // well. Also, the tab whose closure is undone should be selected.
         CriteriaHelper.pollInstrumentationThread(TabUiTestHelper::verifyUndoBarShowingAndClickUndo);
         verifyShowingStrip(cta, false, 2);
         verifyTabModelTabCount(cta, 2, 0);
+        verifyStripSelectedPosition(cta, 1);
 
         // Disable undo snackbar and test continuous closures.
         cta.getSnackbarManager().disableForTesting();

chrome/android/features/tab_ui/junit/src/org/chromium/chrome/browser/tasks/tab_management/TabListMediatorUnitTest.java

@@ -29,6 +29,8 @@ import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
+import static org.chromium.chrome.browser.flags.ChromeFeatureList.CONDITIONAL_TAB_STRIP_ANDROID;
+import static org.chromium.chrome.browser.flags.ChromeFeatureList.TAB_GRID_LAYOUT_ANDROID;
 import static org.chromium.chrome.browser.flags.ChromeFeatureList.TAB_GROUPS_ANDROID;
 import static org.chromium.chrome.browser.flags.ChromeFeatureList.TAB_GROUPS_CONTINUATION_ANDROID;
 import static org.chromium.chrome.browser.tasks.tab_management.MessageCardViewProperties.MESSAGE_TYPE;
@@ -90,6 +92,7 @@ import org.chromium.chrome.browser.tab.TabCreationState;
 import org.chromium.chrome.browser.tab.TabImpl;
 import org.chromium.chrome.browser.tab.TabLaunchType;
 import org.chromium.chrome.browser.tab.TabObserver;
+import org.chromium.chrome.browser.tab.TabSelectionType;
 import org.chromium.chrome.browser.tabmodel.EmptyTabModelFilter;
 import org.chromium.chrome.browser.tabmodel.TabModel;
 import org.chromium.chrome.browser.tabmodel.TabModelFilter;
@@ -825,6 +828,27 @@ public class TabListMediatorUnitTest {
         assertThat(mModel.get(2).model.get(TabProperties.TITLE), equalTo(TAB3_TITLE));
     }
 
+    @Test
+    @Features.EnableFeatures({CONDITIONAL_TAB_STRIP_ANDROID})
+    @Features.DisableFeatures({TAB_GRID_LAYOUT_ANDROID, TAB_GROUPS_ANDROID})
+    public void tabClosureUndone_CTS() {
+        initAndAssertAllProperties();
+
+        TabImpl newTab = prepareTab(TAB3_ID, TAB3_TITLE, TAB3_URL);
+        doReturn(3).when(mTabModel).getCount();
+        doReturn(newTab).when(mTabModel).getTabAt(2);
+        doReturn(Arrays.asList(mTab1, mTab2, newTab))
+                .when(mTabModelFilter)
+                .getRelatedTabList(eq(TAB1_ID));
+
+        mTabModelObserverCaptor.getValue().tabClosureUndone(newTab);
+
+        assertThat(mModel.size(), equalTo(3));
+        assertThat(mModel.get(2).model.get(TabProperties.TAB_ID), equalTo(TAB3_ID));
+        assertThat(mModel.get(2).model.get(TabProperties.TITLE), equalTo(TAB3_TITLE));
+        verify(mTabModel).setIndex(eq(2), eq(TabSelectionType.FROM_USER));
+    }
+
     @Test
     public void tabMergeIntoGroup() {
         setUpForTabGroupOperation(TabListMediatorType.TAB_SWITCHER);