[InstantStart] Closes all tabs should hide tab switcher.

This bug is caused by the StartSurfaceMediator registers an observer to
the empty tab model before the TabModel is initialized. In this CL, we
register an observer to the TabModeSelector first and registers an
normal TabModel observer after the TabModel is initialized.

Bug: 1126914, 1138162
Change-Id: I653aeac99c58ed032e9a604b4001a389832d3452
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2517623
Commit-Queue: Xi Han <hanxi@chromium.org>
Reviewed-by: Yue Zhang <yuezhanggg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825345}

chrome/android/features/start_surface/internal/java/src/org/chromium/chrome/features/start_surface/StartSurfaceMediator.java

@@ -138,7 +138,6 @@ class StartSurfaceMediator
     private int mStartSurfaceState;
     @StartSurfaceState
     private int mPreviousStartSurfaceState;
-    private boolean mIsOmniboxFocused;
     @Nullable
     private TabModel mNormalTabModel;
     @Nullable
@@ -151,6 +150,11 @@ class StartSurfaceMediator
     private boolean mExcludeMVTiles;
     private boolean mShowStackTabSwitcher;
     private OneshotSupplier<StartSurface> mStartSurfaceSupplier;
+    /**
+     * Whether a pending observer needed be added to the normal TabModel after the TabModel is
+     * initialized.
+     */
+    private boolean mPendingObserver;
     /**
      * The value of {@link Pref#ARTICLES_LIST_VISIBLE} on Startup. Getting this value for recording
      * the consistency of {@link ChromePreferenceKeys#FEED_ARTICLES_LIST_VISIBLE} with {@link
@@ -230,12 +234,11 @@ class StartSurfaceMediator
 
                 // Hide tab carousel, which does not exist in incognito mode, when closing all
                 // normal tabs.
-                mNormalTabModel = mTabModelSelector.getModel(false);
                 mNormalTabModelObserver = new TabModelObserver() {
                     @Override
                     public void willCloseTab(Tab tab, boolean animate) {
                         if (mStartSurfaceState == StartSurfaceState.SHOWN_HOMEPAGE
-                                && mNormalTabModel.getCount() <= 1) {
+                                && mTabModelSelector.getModel(false).getCount() <= 1) {
                             setTabCarouselVisibility(false);
                         }
                     }
@@ -256,6 +259,30 @@ class StartSurfaceMediator
                                 mTabModelSelector.getModel(false).getCount() > 0 && !mIsIncognito);
                     }
                 };
+                if (mTabModelSelector.getModels().isEmpty()) {
+                    TabModelSelectorObserver selectorObserver =
+                            new EmptyTabModelSelectorObserver() {
+                                @Override
+                                public void onChange() {
+                                    assert !mTabModelSelector.getModels().isEmpty();
+                                    assert mTabModelSelector.getTabModelFilterProvider()
+                                                    .getTabModelFilter(false)
+                                            != null;
+                                    assert mTabModelSelector.getTabModelFilterProvider()
+                                                    .getTabModelFilter(true)
+                                            != null;
+                                    mTabModelSelector.removeObserver(this);
+                                    mNormalTabModel = mTabModelSelector.getModel(false);
+                                    if (mPendingObserver) {
+                                        mPendingObserver = false;
+                                        mNormalTabModel.addObserver(mNormalTabModelObserver);
+                                    }
+                                }
+                            };
+                    mTabModelSelector.addObserver(selectorObserver);
+                } else {
+                    mNormalTabModel = mTabModelSelector.getModel(false);
+                }
             }
 
             mBrowserControlsObserver = new BrowserControlsStateProvider.Observer() {
@@ -467,8 +494,11 @@ class StartSurfaceMediator
             // bottom bar.
             mPropertyModel.set(
                     BOTTOM_BAR_HEIGHT, mBrowserControlsStateProvider.getBottomControlsHeight());
-            mNormalTabModel.addObserver(mNormalTabModelObserver);
-
+            if (mNormalTabModel != null) {
+                mNormalTabModel.addObserver(mNormalTabModelObserver);
+            } else {
+                mPendingObserver = true;
+            }
         } else if (mStartSurfaceState == StartSurfaceState.SHOWN_TABSWITCHER) {
             mPropertyModel.set(IS_SHOWING_STACK_TAB_SWITCHER, mShowStackTabSwitcher);
 
@@ -669,7 +699,11 @@ class StartSurfaceMediator
                 destroyFeedSurfaceCoordinator();
             }
             if (mNormalTabModelObserver != null) {
-                mNormalTabModel.removeObserver(mNormalTabModelObserver);
+                if (mNormalTabModel != null) {
+                    mNormalTabModel.removeObserver(mNormalTabModelObserver);
+                } else if (mPendingObserver) {
+                    mPendingObserver = false;
+                }
             }
             if (mTabModelSelectorObserver != null) {
                 mTabModelSelector.removeObserver(mTabModelSelectorObserver);

chrome/android/features/start_surface/internal/javatests/src/org/chromium/chrome/features/start_surface/StartSurfaceTest.java

@@ -44,6 +44,7 @@ import android.content.Intent;
 import android.os.Build;
 import android.support.test.InstrumentationRegistry;
 import android.view.KeyEvent;
+import android.view.View;
 import android.view.ViewGroup;
 
 import androidx.test.espresso.ViewAction;
@@ -1124,6 +1125,63 @@ public class StartSurfaceTest {
                             FEED_VISIBILITY_CONSISTENCY, 1));
         }
     }
+
+    @Test
+    @MediumTest
+    @Feature({"StartSurface"})
+    // clang-format off
+    @CommandLineFlags.Add({BASE_PARAMS + "/single"})
+    public void testShow_SingleAsHomepage_CloseAllTabsShouldHideTabSwitcher() {
+        // clang-format on
+        if (!mImmediateReturn) {
+            onView(withId(org.chromium.chrome.tab_ui.R.id.home_button)).perform(click());
+        }
+
+        ChromeTabbedActivity cta = mActivityTestRule.getActivity();
+        CriteriaHelper.pollUiThread(
+                () -> cta.getLayoutManager() != null && cta.getLayoutManager().overviewVisible());
+        waitForTabModel();
+        TabUiTestHelper.verifyTabModelTabCount(cta, 1, 0);
+        assertEquals(cta.findViewById(org.chromium.chrome.tab_ui.R.id.tab_switcher_title)
+                             .getVisibility(),
+                View.VISIBLE);
+
+        TestThreadUtils.runOnUiThreadBlocking(
+                () -> { cta.getTabModelSelector().getModel(false).closeAllTabs(); });
+        TabUiTestHelper.verifyTabModelTabCount(cta, 0, 0);
+        assertEquals(cta.findViewById(org.chromium.chrome.tab_ui.R.id.tab_switcher_title)
+                             .getVisibility(),
+                View.GONE);
+    }
+
+    @Test
+    @MediumTest
+    @Feature({"StartSurface"})
+    // clang-format off
+    @CommandLineFlags.Add({BASE_PARAMS + "/single/exclude_mv_tiles/true"
+            + "/show_last_active_tab_only/true/show_stack_tab_switcher/true"})
+    public void testShow_SingleAsHomepageV2_CloseAllTabsShouldHideTabSwitcher() {
+        // clang-format on
+        if (!mImmediateReturn) {
+            onView(withId(org.chromium.chrome.tab_ui.R.id.home_button)).perform(click());
+        }
+
+        ChromeTabbedActivity cta = mActivityTestRule.getActivity();
+        CriteriaHelper.pollUiThread(
+                () -> cta.getLayoutManager() != null && cta.getLayoutManager().overviewVisible());
+        waitForTabModel();
+        TabUiTestHelper.verifyTabModelTabCount(cta, 1, 0);
+        assertEquals(cta.findViewById(org.chromium.chrome.tab_ui.R.id.tab_switcher_title)
+                             .getVisibility(),
+                View.VISIBLE);
+
+        TestThreadUtils.runOnUiThreadBlocking(
+                () -> { cta.getTabModelSelector().getModel(false).closeAllTabs(); });
+        TabUiTestHelper.verifyTabModelTabCount(cta, 0, 0);
+        assertEquals(cta.findViewById(org.chromium.chrome.tab_ui.R.id.tab_switcher_title)
+                             .getVisibility(),
+                View.GONE);
+    }
 }
 
 // TODO(crbug.com/1033909): Add more integration tests.

chrome/android/features/start_surface/internal/junit/src/org/chromium/chrome/features/start_surface/StartSurfaceMediatorUnitTest.java

@@ -71,6 +71,8 @@ import org.chromium.chrome.browser.tab.Tab;
 import org.chromium.chrome.browser.tab.TabLaunchType;
 import org.chromium.chrome.browser.tabmodel.EmptyTabModelSelectorObserver;
 import org.chromium.chrome.browser.tabmodel.TabModel;
+import org.chromium.chrome.browser.tabmodel.TabModelFilter;
+import org.chromium.chrome.browser.tabmodel.TabModelFilterProvider;
 import org.chromium.chrome.browser.tabmodel.TabModelObserver;
 import org.chromium.chrome.browser.tabmodel.TabModelSelector;
 import org.chromium.chrome.browser.tasks.TasksSurfaceProperties;
@@ -85,6 +87,7 @@ import org.chromium.ui.modelutil.PropertyModel;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.List;
 
 /** Tests for {@link StartSurfaceMediator}. */
 @RunWith(BaseRobolectricTestRunner.class)
@@ -104,6 +107,12 @@ public class StartSurfaceMediatorUnitTest {
     @Mock
     private TabModel mIncognitoTabModel;
     @Mock
+    private List<TabModel> mTabModels;
+    @Mock
+    private TabModelFilterProvider mTabModelFilterProvider;
+    @Mock
+    private TabModelFilter mTabModelFilter;
+    @Mock
     private FakeboxDelegate mFakeBoxDelegate;
     @Mock
     private ExploreSurfaceCoordinator.FeedSurfaceCreator mFeedSurfaceCreator;
@@ -147,6 +156,10 @@ public class StartSurfaceMediatorUnitTest {
         mPropertyModel = new PropertyModel(allProperties);
         mSecondaryTasksSurfacePropertyModel = new PropertyModel(allProperties);
 
+        mTabModels = new ArrayList<>(2);
+        mTabModels.add(mNormalTabModel);
+        mTabModels.add(mIncognitoTabModel);
+        when(mTabModelSelector.getModels()).thenReturn(mTabModels);
         doReturn(mNormalTabModel).when(mTabModelSelector).getModel(false);
         doReturn(mIncognitoTabModel).when(mTabModelSelector).getModel(true);
         doReturn(false).when(mNormalTabModel).isIncognito();
@@ -682,7 +695,79 @@ public class StartSurfaceMediatorUnitTest {
     }
 
     @Test
-    public void addAndRemoveTabModelObserverWithOverview() {
+    public void pendingTabModelObserverWithBothShowOverviewAndHideBeforeTabModelInitialization() {
+        doReturn(false).when(mTabModelSelector).isIncognitoSelected();
+        doReturn(mVoiceRecognitionHandler).when(mFakeBoxDelegate).getVoiceRecognitionHandler();
+        doReturn(true).when(mVoiceRecognitionHandler).isVoiceSearchEnabled();
+
+        mTabModels.clear();
+        StartSurfaceMediator mediator = createStartSurfaceMediator(SurfaceMode.SINGLE_PANE, false);
+        verify(mTabModelSelector).addObserver(mTabModelSelectorObserverCaptor.capture());
+
+        mediator.setOverviewState(StartSurfaceState.SHOWN_HOMEPAGE);
+        mediator.showOverview(false);
+        verify(mNormalTabModel, never()).addObserver(mTabModelObserverCaptor.capture());
+        mediator.startedHiding();
+        verify(mNormalTabModel, never()).addObserver(mTabModelObserverCaptor.capture());
+        verify(mNormalTabModel, never()).removeObserver(mTabModelObserverCaptor.capture());
+    }
+
+    @Test
+    public void pendingTabModelObserverWithShowOverviewBeforeAndHideAfterTabModelInitialization() {
+        doReturn(false).when(mTabModelSelector).isIncognitoSelected();
+        doReturn(mVoiceRecognitionHandler).when(mFakeBoxDelegate).getVoiceRecognitionHandler();
+        doReturn(true).when(mVoiceRecognitionHandler).isVoiceSearchEnabled();
+
+        mTabModels.clear();
+        StartSurfaceMediator mediator = createStartSurfaceMediator(SurfaceMode.SINGLE_PANE, false);
+        verify(mTabModelSelector).addObserver(mTabModelSelectorObserverCaptor.capture());
+
+        mediator.setOverviewState(StartSurfaceState.SHOWN_HOMEPAGE);
+        mediator.showOverview(false);
+        verify(mNormalTabModel, never()).addObserver(mTabModelObserverCaptor.capture());
+
+        mTabModels.add(mNormalTabModel);
+        mTabModels.add(mIncognitoTabModel);
+        when(mTabModelSelector.getTabModelFilterProvider()).thenReturn(mTabModelFilterProvider);
+        when(mTabModelFilterProvider.getTabModelFilter(false)).thenReturn(mTabModelFilter);
+        when(mTabModelFilterProvider.getTabModelFilter(true)).thenReturn(mTabModelFilter);
+        mTabModelSelectorObserverCaptor.getValue().onChange();
+        verify(mTabModelSelector).removeObserver(mTabModelSelectorObserverCaptor.capture());
+        verify(mNormalTabModel).addObserver(mTabModelObserverCaptor.capture());
+
+        mediator.startedHiding();
+        verify(mNormalTabModel).removeObserver(mTabModelObserverCaptor.capture());
+    }
+
+    @Test
+    public void pendingTabModelObserverWithBothShowAndHideOverviewAfterTabModelInitialization() {
+        doReturn(false).when(mTabModelSelector).isIncognitoSelected();
+        doReturn(mVoiceRecognitionHandler).when(mFakeBoxDelegate).getVoiceRecognitionHandler();
+        doReturn(true).when(mVoiceRecognitionHandler).isVoiceSearchEnabled();
+
+        mTabModels.clear();
+        StartSurfaceMediator mediator = createStartSurfaceMediator(SurfaceMode.SINGLE_PANE, false);
+        verify(mTabModelSelector).addObserver(mTabModelSelectorObserverCaptor.capture());
+
+        mTabModels.add(mNormalTabModel);
+        mTabModels.add(mIncognitoTabModel);
+        when(mTabModelSelector.getTabModelFilterProvider()).thenReturn(mTabModelFilterProvider);
+        when(mTabModelFilterProvider.getTabModelFilter(false)).thenReturn(mTabModelFilter);
+        when(mTabModelFilterProvider.getTabModelFilter(true)).thenReturn(mTabModelFilter);
+        mTabModelSelectorObserverCaptor.getValue().onChange();
+        verify(mTabModelSelector).removeObserver(mTabModelSelectorObserverCaptor.capture());
+        verify(mNormalTabModel, never()).addObserver(mTabModelObserverCaptor.capture());
+
+        mediator.setOverviewState(StartSurfaceState.SHOWN_HOMEPAGE);
+        mediator.showOverview(false);
+        verify(mNormalTabModel).addObserver(mTabModelObserverCaptor.capture());
+
+        mediator.startedHiding();
+        verify(mNormalTabModel).removeObserver(mTabModelObserverCaptor.capture());
+    }
+
+    @Test
+    public void addAndRemoveTabModelSelectorObserverWithOverviewAfterTabModelInitialization() {
         doReturn(false).when(mTabModelSelector).isIncognitoSelected();
         doReturn(mVoiceRecognitionHandler).when(mFakeBoxDelegate).getVoiceRecognitionHandler();
         doReturn(true).when(mVoiceRecognitionHandler).isVoiceSearchEnabled();