Fix initial scroll for TabSwitcherOnReturn

INITIAL_SCROLL_INDEX_OFFSET was not properly set if tab restoration
finishes after tab switcher is shown.

Bug: 1022289
Change-Id: I63d18d0fae7b6e6d40865667f7bd0fecdd684f4d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1903526
Commit-Queue: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Reviewed-by: Yue Zhang <yuezhanggg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714023}

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

@@ -234,6 +234,7 @@ class TabSwitcherMediator implements TabSwitcher.Controller, TabListRecyclerView
                 mResetHandler.resetWithTabList(
                         mTabModelSelector.getTabModelFilterProvider().getCurrentTabModelFilter(),
                         false, mShowTabsInMruOrder);
+                setInitialScrollIndexOffset();
             }
         };
 
@@ -420,15 +421,20 @@ class TabSwitcherMediator implements TabSwitcher.Controller, TabListRecyclerView
         mHandler.removeCallbacks(mSoftClearTabListRunnable);
         mHandler.removeCallbacks(mClearTabListRunnable);
         boolean quick = false;
-        if (TabFeatureUtilities.isTabToGtsAnimationEnabled()
-                && mTabModelSelector.getTabModelFilterProvider()
-                           .getCurrentTabModelFilter()
-                           .isTabModelRestored()) {
-            quick = mResetHandler.resetWithTabList(
-                    mTabModelSelector.getTabModelFilterProvider().getCurrentTabModelFilter(), false,
-                    mShowTabsInMruOrder);
+        if (mTabModelSelector.getTabModelFilterProvider()
+                        .getCurrentTabModelFilter()
+                        .isTabModelRestored()) {
+            if (TabFeatureUtilities.isTabToGtsAnimationEnabled()) {
+                quick = mResetHandler.resetWithTabList(
+                        mTabModelSelector.getTabModelFilterProvider().getCurrentTabModelFilter(),
+                        false, mShowTabsInMruOrder);
+            }
+            setInitialScrollIndexOffset();
         }
+        return quick;
+    }
 
+    private void setInitialScrollIndexOffset() {
         int initialPosition = Math.max(
                 mTabModelSelector.getTabModelFilterProvider().getCurrentTabModelFilter().index()
                         - INITIAL_SCROLL_INDEX_OFFSET,
@@ -436,7 +442,6 @@ class TabSwitcherMediator implements TabSwitcher.Controller, TabListRecyclerView
         // In MRU order, selected Tab is always at the first position.
         if (mShowTabsInMruOrder) initialPosition = 0;
         mContainerViewModel.set(INITIAL_SCROLL_INDEX, initialPosition);
-        return quick;
     }
 
     @Override

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

@@ -466,6 +466,18 @@ public class TabSwitcherMediatorUnitTest {
         verify(mResetHandler).resetWithTabList(mTabModelFilter, false, false);
     }
 
+    @Test
+    public void setInitialScrollIndexOnRestoreCompleted() {
+        initAndAssertAllProperties();
+        mMediator.showOverview(true);
+        assertThat(mModel.get(TabListContainerProperties.IS_VISIBLE), equalTo(true));
+
+        mModel.set(TabListContainerProperties.INITIAL_SCROLL_INDEX, 1);
+
+        mTabModelObserverCaptor.getValue().restoreCompleted();
+        assertThat(mModel.get(TabListContainerProperties.INITIAL_SCROLL_INDEX), equalTo(0));
+    }
+
     @Test
     public void showOverviewDoesNotUpdateResetHandlerBeforeRestoreCompleted() {
         initAndAssertAllProperties();
@@ -508,6 +520,17 @@ public class TabSwitcherMediatorUnitTest {
         verify(mResetHandler).resetWithTabList(mTabModelFilter, false, false);
     }
 
+    @Test
+    public void prepareOverviewSetsInitialScrollIndexAfterRestoreCompleted() {
+        initAndAssertAllProperties();
+        doReturn(true).when(mTabModelFilter).isTabModelRestored();
+
+        mModel.set(TabListContainerProperties.INITIAL_SCROLL_INDEX, 1);
+
+        mMediator.prepareOverview();
+        assertThat(mModel.get(TabListContainerProperties.INITIAL_SCROLL_INDEX), equalTo(0));
+    }
+
     @Test
     @DisableFeatures(ChromeFeatureList.TAB_GROUPS_UI_IMPROVEMENTS_ANDROID)
     public void openDialogButton_FlagDisabled() {

chrome/android/javatests/src/org/chromium/chrome/browser/tasks/ReturnToChromeTest.java

@@ -27,6 +27,7 @@ import org.chromium.chrome.browser.tasks.tab_management.TabUiTestHelper;
 import org.chromium.chrome.test.ChromeJUnit4ClassRunner;
 import org.chromium.chrome.test.ChromeTabbedActivityTestRule;
 import org.chromium.chrome.test.util.ApplicationTestUtils;
+import org.chromium.chrome.test.util.RenderTestRule;
 import org.chromium.content_public.browser.test.util.Criteria;
 import org.chromium.content_public.browser.test.util.CriteriaHelper;
 import org.chromium.net.test.EmbeddedTestServer;
@@ -49,6 +50,9 @@ public class ReturnToChromeTest {
 
     private String mUrl;
 
+    @Rule
+    public RenderTestRule mRenderTestRule = new RenderTestRule();
+
     @Before
     public void setUp() {
         FeatureUtilities.setGridTabSwitcherEnabledForTesting(true);
@@ -101,4 +105,30 @@ public class ReturnToChromeTest {
 
         assertEquals(2, mActivityTestRule.getActivity().getTabModelSelector().getTotalTabCount());
     }
+
+    @Test
+    @SmallTest
+    @Feature({"ReturnToChrome", "RenderTest"})
+    @CommandLineFlags.Add({BASE_PARAMS + "/" + TAB_SWITCHER_ON_RETURN_MS + "/0"})
+    public void testInitialScrollIndex() throws Exception {
+        TabUiTestHelper.prepareTabsWithThumbnail(mActivityTestRule, 10, 0, mUrl);
+        ApplicationTestUtils.finishActivity(mActivityTestRule.getActivity());
+
+        mActivityTestRule.startMainActivityFromLauncher();
+
+        Assert.assertTrue(mActivityTestRule.getActivity().getLayoutManager().overviewVisible());
+
+        CriteriaHelper.pollUiThread(Criteria.equals(true,
+                mActivityTestRule.getActivity()
+                        .getTabModelSelector()
+                        .getTabModelFilterProvider()
+                        .getCurrentTabModelFilter()::isTabModelRestored));
+
+        assertEquals(10, mActivityTestRule.getActivity().getTabModelSelector().getTotalTabCount());
+        assertEquals(9, mActivityTestRule.getActivity().getCurrentTabModel().index());
+        // Make sure the grid tab switcher is scrolled down to show the selected tab.
+        mRenderTestRule.render(mActivityTestRule.getActivity().findViewById(
+                                       org.chromium.chrome.tab_ui.R.id.tab_list_view),
+                "10_web_tabs-select_last");
+    }
 }

chrome/test/data/android/render_tests/ReturnToChromeTest.10_web_tabs-select_last.Nexus_5-19.png.sha1

+ca7317919b3080d8417090e4dca23f1329353842
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