[M110] Fix being unable to exit tab switcher if last tab is closed by…

… site

This happens when user enters overview mode and at the same time
tabs are closed by the sites itself.

Because the tabs are not closed by user's input, tabPendingClosure is
not triggered such that the back press state is out-of-update.

Override onFinishingTabClosure in order to correctly trigger
notifyBackPressStateChangedInternal in this scenario.

(cherry picked from commit 4ff3da2)

Bug: 1401162
Change-Id: I2deeb41ff55819b46ea42fd34ad82467b57c3605
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4108260
Commit-Queue: Lijin Shen <lazzzis@google.com>
Reviewed-by: Mei Liang <meiliang@chromium.org>
Cr-Original-Commit-Position: refs/heads/main@{#1086021}
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4133939
Reviewed-by: Yue Zhang <yuezhanggg@chromium.org>
Cr-Commit-Position: refs/branch-heads/5481@{#125}
Cr-Branched-From: 130f3e4-refs/heads/main@{#1084008}

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

@@ -38,6 +38,7 @@
 import org.chromium.base.supplier.ObservableSupplierImpl;
 import org.chromium.base.supplier.OneshotSupplier;
 import org.chromium.base.task.PostTask;
+import org.chromium.chrome.browser.back_press.BackPressManager;
 import org.chromium.chrome.browser.browser_controls.BrowserControlsStateProvider;
 import org.chromium.chrome.browser.compositor.layouts.LayoutManagerImpl;
 import org.chromium.chrome.browser.compositor.layouts.content.TabContentManager;
@@ -426,6 +427,18 @@ public void tabPendingClosure(Tab tab) {
                 notifyBackPressStateChangedInternal();
             }
 
+            @Override
+            public void onFinishingTabClosure(Tab tab) {
+                // If tab is closed by the site itself rather than user's input,
+                // tabPendingClosure & tabClosureCommitted won't be called.
+                notifyBackPressStateChangedInternal();
+            }
+
+            @Override
+            public void tabRemoved(Tab tab) {
+                notifyBackPressStateChangedInternal();
+            }
+
             @Override
             public void multipleTabsPendingClosure(List<Tab> tabs, boolean isAllTabs) {
                 notifyBackPressStateChangedInternal();
@@ -880,7 +893,10 @@ public boolean onBackPressed(boolean isOnHomepage) {
             return true;
         }
 
-        if (!mContainerViewModel.get(IS_VISIBLE)) return false;
+        if (!mContainerViewModel.get(IS_VISIBLE)) {
+            assert !BackPressManager.isEnabled() : "Invisible container: Backpress must be handled";
+            return false;
+        }
 
         if (mTabGridDialogController != null && mTabGridDialogController.handleBackPressed()) {
             return true;
@@ -889,7 +905,10 @@ public boolean onBackPressed(boolean isOnHomepage) {
         // When the Start surface is showing, we no longer need to call onTabSelecting().
         if (isOnHomepage && mMode == TabListCoordinator.TabListMode.CAROUSEL) return false;
 
-        if (mTabModelSelector.getCurrentTab() == null) return false;
+        if (mTabModelSelector.getCurrentTab() == null) {
+            assert !BackPressManager.isEnabled() : "No tab: Backpress must be handled";
+            return false;
+        }
 
         onTabSelecting(mTabModelSelector.getCurrentTabId(), false);
 

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

@@ -996,6 +996,40 @@ public void testBackPressAfterSwitchIncognitoMode() {
         Assert.assertEquals(Boolean.FALSE, mMediator.getHandleBackPressChangedSupplier().get());
     }
 
+    @Test
+    @EnableFeatures({ChromeFeatureList.BACK_GESTURE_REFACTOR})
+    public void testBackPressAfterTabClosedBySite() {
+        initAndAssertAllProperties();
+        Assert.assertFalse(mMediator.shouldInterceptBackPress());
+
+        mModel.set(TabListContainerProperties.IS_VISIBLE, true);
+        doReturn(false).when(mTabModelFilter).isIncognito();
+        doReturn(false).when(mTabModelSelector).isIncognitoSelected();
+        doReturn(true).when(mTabModelSelector).isTabStateInitialized();
+        doReturn(false).when(mIncognitoReauthController).isIncognitoReauthPending();
+        doReturn(true).when(mTabModel).isIncognito();
+        doReturn(mTab1).when(mTabModelSelector).getCurrentTab();
+
+        mTabModelSelectorObserverCaptor.getValue().onTabModelSelected(mTabModel, null);
+        mMediator.showTabSwitcherView(true);
+        Assert.assertTrue(mMediator.shouldInterceptBackPress());
+        Assert.assertEquals(Boolean.TRUE, mMediator.getHandleBackPressChangedSupplier().get());
+
+        // If tab is closed by the site rather than user's input, only
+        // onFinishingTabClosure will be triggered.
+        mModel.set(TabListContainerProperties.IS_VISIBLE, true);
+        doReturn(false).when(mTabModelFilter).isIncognito();
+        doReturn(false).when(mTabModelSelector).isIncognitoSelected();
+        doReturn(true).when(mTabModelSelector).isTabStateInitialized();
+        doReturn(false).when(mIncognitoReauthController).isIncognitoReauthPending();
+        doReturn(false).when(mTabModel).isIncognito();
+        doReturn(null).when(mTabModelSelector).getCurrentTab();
+
+        mTabModelObserverCaptor.getValue().onFinishingTabClosure(mTab1);
+        Assert.assertFalse(mMediator.shouldInterceptBackPress());
+        Assert.assertEquals(Boolean.FALSE, mMediator.getHandleBackPressChangedSupplier().get());
+    }
+
     @Test
     public void testOnTabModelSelected_NewModelIncognito_ReauthPending_ClearsTabList() {
         initAndAssertAllProperties();