[116][Fixit][Tablet] Show tab switcher if no regular tab when toggle …

…incognito

(cherry picked from commit e0b9d5b)

Bug: 1458710
Change-Id: Ie9fe078a0941f49375d835ff232826a4c5b54420
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4654995
Reviewed-by: Matthew Jones <mdjones@chromium.org>
Reviewed-by: Neil Coronado <nemco@google.com>
Code-Coverage: Findit <findit-for-me@appspot.gserviceaccount.com>
Commit-Queue: Mei Liang <meiliang@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1164227}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4667874
Reviewed-by: Theresa Sullivan <twellington@chromium.org>
Cr-Commit-Position: refs/branch-heads/5845@{#329}
Cr-Branched-From: 5a5dff6-refs/heads/main@{#1160321}

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

@@ -278,6 +278,33 @@ public void testGridTabSwitcherOnCloseAllTabs() throws ExecutionException {
                 .check(matches(withEffectiveVisibility(VISIBLE)));
     }
 
+    @Test
+    @MediumTest
+    public void testGridTabSwitcherToggleIncognitoWithNoRegularTab() throws ExecutionException {
+        // Close all the regular tabs.
+        TestThreadUtils.runOnUiThreadBlocking(() -> {
+            sActivityTestRule.getActivity().getCurrentTabModel().closeTab(
+                    sActivityTestRule.getActivity().getActivityTab());
+        });
+        assertEquals("Expected to be 0 tabs in regular model", 0,
+                sActivityTestRule.getActivity()
+                        .getTabModelSelectorSupplier()
+                        .get()
+                        .getModel(false)
+                        .getCount());
+        // Open an incognito tab.
+        prepareTabs(0, 1);
+        assertTrue("Expected to be in Incognito model",
+                sActivityTestRule.getActivity().getCurrentTabModel().isIncognito());
+        // Assert the grid tab switcher is not yet showing.
+        onView(withId(R.id.tab_switcher_view_holder)).check(matches(withEffectiveVisibility(GONE)));
+        // Toggle to normal switcher.
+        clickIncognitoToggleButton();
+        // Assert the grid tab switcher is shown automatically, since there is no regular tab.
+        onView(withId(R.id.tab_switcher_view_holder))
+                .check(matches(withEffectiveVisibility(VISIBLE)));
+    }
+
     @Test
     @MediumTest
     @EnableFeatures({ChromeFeatureList.START_SURFACE_REFACTOR})

chrome/android/java/src/org/chromium/chrome/browser/compositor/layouts/LayoutManagerChromeTablet.java

@@ -148,6 +148,10 @@ public void onTabsAllClosing(boolean incognito) {
     protected void tabModelSwitched(boolean incognito) {
         super.tabModelSwitched(incognito);
         getTabModelSelector().commitAllTabClosures();
+        if (getActiveLayout() == mStaticLayout && !incognito
+                && getTabModelSelector().getModel(false).getCount() == 0) {
+            showLayout(LayoutType.TAB_SWITCHER, /*animate=*/false);
+        }
     }
 
     @Override