Partially revert TabListMediator initialization

This CL reverts the changes in TabListMediator initialization in
http://crrev.com/c/2326858 to help identify the cause of a related
crash.

Bug: 1116985, 1111122
Change-Id: Ib1131418ac0ce6f60a76d3dea23ea80eb5a2ca03
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2375885
Commit-Queue: Yue Zhang <yuezhanggg@chromium.org>
Reviewed-by: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801552}

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

@@ -38,7 +38,6 @@
 import static org.chromium.chrome.browser.tasks.tab_management.TabUiTestHelper.finishActivity;
 import static org.chromium.chrome.browser.tasks.tab_management.TabUiTestHelper.getSwipeToDismissAction;
 import static org.chromium.chrome.browser.tasks.tab_management.TabUiTestHelper.leaveTabSwitcher;
-import static org.chromium.chrome.browser.tasks.tab_management.TabUiTestHelper.mergeAllNormalTabsToAGroup;
 import static org.chromium.chrome.browser.tasks.tab_management.TabUiTestHelper.rotateDeviceToOrientation;
 import static org.chromium.chrome.browser.tasks.tab_management.TabUiTestHelper.switchTabModel;
 import static org.chromium.chrome.browser.tasks.tab_management.TabUiTestHelper.verifyTabModelTabCount;
@@ -2022,14 +2021,6 @@ public void testSetup_WithInstantStart() throws Exception {
         // closure.
         closeFirstTabInTabSwitcher();
         verifyTabSwitcherCardCount(cta, 0);
-
-        // Verify TabGroupModelFilter is correctly setup by checking if tab switcher changes with
-        // tab grouping.
-        createTabs(cta, false, 3);
-        enterTabSwitcher(cta);
-        verifyTabSwitcherCardCount(cta, 2);
-        mergeAllNormalTabsToAGroup(cta);
-        verifyTabSwitcherCardCount(cta, 1);
     }
 
     private void enterTabGroupManualSelection(ChromeTabbedActivity cta) {

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

@@ -567,7 +567,8 @@ public void tabRemoved(Tab tab) {
             }
         };
 
-        if (TabUiFeatureUtilities.isTabGroupsAndroidEnabled()) {
+        if (mTabModelSelector.getTabModelFilterProvider().getCurrentTabModelFilter()
+                        instanceof TabGroupModelFilter) {
             mTabGroupObserver = new EmptyTabGroupModelFilterObserver() {
                 @Override
                 public void didMoveWithinGroup(
@@ -695,6 +696,13 @@ public void didMoveTabGroup(
                 public void didCreateGroup(
                         List<Tab> tabs, List<Integer> tabOriginalIndex, boolean isSameGroup) {}
             };
+
+            ((TabGroupModelFilter) mTabModelSelector.getTabModelFilterProvider().getTabModelFilter(
+                     false))
+                    .addTabGroupObserver(mTabGroupObserver);
+            ((TabGroupModelFilter) mTabModelSelector.getTabModelFilterProvider().getTabModelFilter(
+                     true))
+                    .addTabGroupObserver(mTabGroupObserver);
         }
 
         // TODO(meiliang): follow up with unit tests to test the close signal is sent correctly with
@@ -758,17 +766,6 @@ public void initWithNative(Profile profile) {
         mTabListFaviconProvider.initWithNative(profile);
         mTabModelSelector.getTabModelFilterProvider().addTabModelFilterObserver(mTabModelObserver);
 
-        if (mTabGroupObserver != null) {
-            assert mTabModelSelector.getTabModelFilterProvider().getCurrentTabModelFilter()
-                            instanceof TabGroupModelFilter;
-            ((TabGroupModelFilter) mTabModelSelector.getTabModelFilterProvider().getTabModelFilter(
-                     false))
-                    .addTabGroupObserver(mTabGroupObserver);
-            ((TabGroupModelFilter) mTabModelSelector.getTabModelFilterProvider().getTabModelFilter(
-                     true))
-                    .addTabGroupObserver(mTabGroupObserver);
-        }
-
         if (TabUiFeatureUtilities.isTabGroupsAndroidContinuationEnabled()) {
             mTabGroupTitleEditor = new TabGroupTitleEditor(mTabModelSelector) {
                 @Override

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

@@ -784,6 +784,7 @@ public void testRenderDialog_5Tabs_InitialScroll(boolean nightModeEnabled) throw
 
     @Test
     @MediumTest
+    @DisabledTest(message = "Re-enable this when crbug.com/1116985 is resolved.")
     @Features.EnableFeatures({ChromeFeatureList.INSTANT_START})
     public void testSetup_WithInstantStart() {
         final ChromeTabbedActivity cta = mActivityTestRule.getActivity();

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

@@ -2342,11 +2342,7 @@ private void setUpForTabGroupOperation(@TabListMediatorType int type) {
                 mTabContentManager::getTabThumbnailWithCallback, mTitleProvider,
                 mTabListFaviconProvider, actionOnRelatedTabs, null, null, handler,
                 getClass().getSimpleName(), uiType);
-
-        // TabGroupModelFilterObserver is registered when native is ready.
-        assertThat(mTabGroupModelFilterObserverCaptor.getAllValues().isEmpty(), equalTo(true));
         mMediator.initWithNative(mProfile);
-        assertThat(mTabGroupModelFilterObserverCaptor.getAllValues().isEmpty(), equalTo(false));
 
         // There are two TabModelObserver and two TabGroupModelFilter.Observer added when
         // initializing TabListMediator, one set from TabListMediator and the other from