Fix IllegalStateException for incognito Tab Reparenting

When the browser is recreated after a theme swap, the current model
isn't necessarily the same before/after recreate() is called.

Bug: 1042565
Change-Id: Icc63273b1690ec0fc5101c0abd252e0eef816469
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2006269Reviewed-by: Yusuf Ozuysal <yusufo@chromium.org>
Commit-Queue: Brandon Wylie <wylieb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732979}

chrome/android/java/src/org/chromium/chrome/browser/night_mode/NightModeReparentingController.java

@@ -62,10 +62,17 @@ public class NightModeReparentingController
             final ReparentingTask reparentingTask =
                     ReparentingTask.get(reparentingParams.getTabToReparent());
             if (reparentingTask == null) continue;
+
+            final TabModel tabModel = mDelegate.getTabModelSelector().getModel(
+                    reparentingParams.getTabToReparent().isIncognito());
+            if (tabModel == null) {
+                AsyncTabParamsManager.remove(tabId);
+                return;
+            }
+
             reparentingTask.finish(mReparentingDelegate, () -> {
-                mDelegate.getTabModelSelector().getCurrentModel().addTab(
-                        reparentingParams.getTabToReparent(), reparentingParams.getTabIndex(),
-                        TabLaunchType.FROM_REPARENTING);
+                tabModel.addTab(reparentingParams.getTabToReparent(),
+                        reparentingParams.getTabIndex(), TabLaunchType.FROM_REPARENTING);
                 AsyncTabParamsManager.remove(tabId);
             });
         }
@@ -80,6 +87,7 @@ public class NightModeReparentingController
         Tab tabToDetach = mDelegate.getActivityTabProvider().get();
         if (tabToDetach == null) return;
         TabModel currentTabModel = mDelegate.getTabModelSelector().getCurrentModel();
+        if (currentTabModel == null) return;
 
         TabReparentingParams params = new TabReparentingParams(tabToDetach, null, null);
         params.setTabIndex(currentTabModel.indexOf(tabToDetach));

chrome/android/junit/src/org/chromium/chrome/browser/night_mode/NightModeReparentingControllerTest.java

@@ -4,6 +4,7 @@
 
 package org.chromium.chrome.browser.night_mode;
 
+import static org.mockito.ArgumentMatchers.anyBoolean;
 import static org.mockito.ArgumentMatchers.anyObject;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.times;
@@ -61,6 +62,7 @@ public class NightModeReparentingControllerTest {
                 // setup
                 mTabModelSelector = Mockito.mock(TabModelSelector.class);
                 doReturn(getCurrentTabModel()).when(mTabModelSelector).getCurrentModel();
+                doReturn(getCurrentTabModel()).when(mTabModelSelector).getModel(anyBoolean());
             }
 
             return mTabModelSelector;
@@ -125,6 +127,18 @@ public class NightModeReparentingControllerTest {
         verify(mTask, times(1)).finish(anyObject(), anyObject());
     }
 
+    @Test
+    public void testReparenting_singleTab_currentModelNullOnStart() {
+        createAndAddMockTab(1, 0);
+        mController.onNightModeStateChanged();
+
+        doReturn(null).when(mDelegate.getTabModelSelector()).getModel(anyBoolean());
+        mController.onStartWithNative();
+
+        AsyncTabParams params = AsyncTabParamsManager.getAsyncTabParams().get(1);
+        Assert.assertNull(params);
+    }
+
     @Test
     public void testReparenting_multipleTabs_onlyOneIsReparented() {
         createAndAddMockTab(1, 0);