Remove desktop tasks on back navigation.

This change makes sure that when we get closing type transition(CLOSE or
TO_BACK), the trigger task is removed. As a result is task is removed
from recents. Initial manual testing showed the approach as sound but we
will be monitoring during flag ramp up to make sure we don't miss any
edge cases.

For the tests, altered the current tests to test the following 3
conditions:
- Wallpaper disabled, back nav disabled
- Wallpaper enabled, back nav disabled
- Wallpaper enabled, back nav enabled

Bug; 352266521
Test: atest DesktopTasksControllerTest
Flag: com.android.window.flags.enable_desktop_windowing_back_navigation

Change-Id: I6cccdb9a0c0d31e34f671b9484cc37804fba6fd2

2 files changed, 283 insertions, 51 deletions

diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/desktopmode/DesktopTasksController.kt b/libs/WindowManager/Shell/src/com/android/wm/shell/desktopmode/DesktopTasksController.kt
index 18157d6255e3..bb344bdb8158 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/desktopmode/DesktopTasksController.kt
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/desktopmode/DesktopTasksController.kt
@@ -1048,14 +1048,12 @@ class DesktopTasksController(
 
     /** Handle task closing by removing wallpaper activity if it's the last active task */
     private fun handleTaskClosing(task: RunningTaskInfo): WindowContainerTransaction? {
-        val wct = if (
-            desktopModeTaskRepository.isOnlyVisibleNonClosingTask(task.taskId) &&
-                desktopModeTaskRepository.wallpaperActivityToken != null
-        ) {
+        ProtoLog.v(WM_SHELL_DESKTOP_MODE, "DesktopTasksController: handleTaskClosing")
+        val wct = WindowContainerTransaction()
+        if (desktopModeTaskRepository.isOnlyVisibleNonClosingTask(task.taskId)
+            && desktopModeTaskRepository.wallpaperActivityToken != null) {
             // Remove wallpaper activity when the last active task is removed
-            WindowContainerTransaction().also { wct -> removeWallpaperActivity(wct) }
-        } else {
-            null
+            removeWallpaperActivity(wct)
         }
         if (!desktopModeTaskRepository.addClosingTask(task.displayId, task.taskId)) {
             // Could happen if the task hasn't been removed from closing list after it disappeared
@@ -1065,7 +1063,12 @@ class DesktopTasksController(
                 task.taskId
             )
         }
-        return wct
+        // If a CLOSE or TO_BACK is triggered on a desktop task, remove the task.
+        if (Flags.enableDesktopWindowingBackNavigation() &&
+            desktopModeTaskRepository.isVisibleTask(task.taskId)) {
+            wct.removeTask(task.token)
+        }
+        return if (wct.isEmpty) null else wct
     }
 
     private fun addMoveToDesktopChanges(
diff --git a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/desktopmode/DesktopTasksControllerTest.kt b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/desktopmode/DesktopTasksControllerTest.kt
index 6cabbf90bbc2..c46c0880101f 100644
--- a/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/desktopmode/DesktopTasksControllerTest.kt
+++ b/libs/WindowManager/Shell/tests/unittest/src/com/android/wm/shell/desktopmode/DesktopTasksControllerTest.kt
@@ -20,7 +20,6 @@ import android.app.ActivityManager.RecentTaskInfo
 import android.app.ActivityManager.RunningTaskInfo
 import android.app.KeyguardManager
 import android.app.WindowConfiguration.ACTIVITY_TYPE_HOME
-import com.android.window.flags.Flags.FLAG_ENABLE_DESKTOP_WINDOWING_MODE
 import android.app.WindowConfiguration.ACTIVITY_TYPE_STANDARD
 import android.app.WindowConfiguration.WINDOWING_MODE_FREEFORM
 import android.app.WindowConfiguration.WINDOWING_MODE_FULLSCREEN
@@ -68,6 +67,7 @@ import com.android.dx.mockito.inline.extended.ExtendedMockito.mockitoSession
 import com.android.dx.mockito.inline.extended.ExtendedMockito.never
 import com.android.dx.mockito.inline.extended.StaticMockitoSession
 import com.android.window.flags.Flags
+import com.android.window.flags.Flags.FLAG_ENABLE_DESKTOP_WINDOWING_MODE
 import com.android.wm.shell.MockToken
 import com.android.wm.shell.RootTaskDisplayAreaOrganizer
 import com.android.wm.shell.ShellTaskOrganizer
@@ -125,11 +125,11 @@ import org.mockito.Mockito.clearInvocations
 import org.mockito.Mockito.mock
 import org.mockito.Mockito.spy
 import org.mockito.Mockito.verify
-import org.mockito.Mockito.`when` as whenever
 import org.mockito.kotlin.anyOrNull
 import org.mockito.kotlin.atLeastOnce
 import org.mockito.kotlin.capture
 import org.mockito.quality.Strictness
+import org.mockito.Mockito.`when` as whenever
 
 /**
  * Test class for {@link DesktopTasksController}
@@ -1348,7 +1348,7 @@ class DesktopTasksControllerTest : ShellTestCase() {
             .setActivityType(ACTIVITY_TYPE_STANDARD)
             .setWindowingMode(WINDOWING_MODE_FULLSCREEN)
             .build()
-    val transition = createTransition(task = task, type = WindowManager.TRANSIT_CLOSE)
+    val transition = createTransition(task = task, type = TRANSIT_CLOSE)
     val result = controller.handleRequest(Binder(), transition)
     assertThat(result).isNull()
   }
@@ -1442,8 +1442,11 @@ class DesktopTasksControllerTest : ShellTestCase() {
   }
 
   @Test
-  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_backTransition_singleActiveTaskNoTokenFlagDisabled_doesNotHandle() {
+  @DisableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION,
+  )
+  fun handleRequest_backTransition_singleActiveTaskNoToken_wallpaperDisabled_backNavDisabled_doesNotHandle() {
     val task = setUpFreeformTask()
 
     val result = controller.handleRequest(Binder(), createTransition(task, type = TRANSIT_TO_BACK))
@@ -1452,8 +1455,22 @@ class DesktopTasksControllerTest : ShellTestCase() {
   }
 
   @Test
+  @EnableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_backTransition_singleActiveTaskNoToken_wallpaperEnabled_backNavEnabled_removesTask() {
+    val task = setUpFreeformTask()
+
+    val result = controller.handleRequest(Binder(), createTransition(task, type = TRANSIT_TO_BACK))
+
+    assertNotNull(result, "Should handle request").assertRemoveAt(0, task.token)
+  }
+
+  @Test
   @EnableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_backTransition_singleActiveTaskNoTokenFlagEnabled_doesNotHandle() {
+  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION)
+  fun handleRequest_backTransition_singleActiveTaskNoToken_backNavigationDisabled_doesNotHandle() {
     val task = setUpFreeformTask()
 
     val result = controller.handleRequest(Binder(), createTransition(task, type = TRANSIT_TO_BACK))
@@ -1462,8 +1479,11 @@ class DesktopTasksControllerTest : ShellTestCase() {
   }
 
   @Test
-  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_backTransition_singleActiveTaskWithTokenFlagDisabled_doesNotHandle() {
+  @DisableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_backTransition_singleActiveTaskWithToken_wallpaperDisabled_backNavDisabled_doesNotHandle() {
     val task = setUpFreeformTask()
 
     desktopModeTaskRepository.wallpaperActivityToken = MockToken().token()
@@ -1473,22 +1493,42 @@ class DesktopTasksControllerTest : ShellTestCase() {
   }
 
   @Test
+  @EnableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_backTransition_singleActiveTaskWithToken_wallpaperEnabled_backNavEnabled_removesWallpaperAndTask() {
+    val task = setUpFreeformTask()
+    val wallpaperToken = MockToken().token()
+
+    desktopModeTaskRepository.wallpaperActivityToken = wallpaperToken
+    val result = controller.handleRequest(Binder(), createTransition(task, type = TRANSIT_TO_BACK))
+
+    // Should create remove wallpaper transaction
+    assertNotNull(result, "Should handle request").assertRemoveAt(index = 0, wallpaperToken)
+    result.assertRemoveAt(index = 1, task.token)
+  }
+
+  @Test
   @EnableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_backTransition_singleActiveTaskWithTokenFlagEnabled_handlesRequest() {
+  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION)
+  fun handleRequest_backTransition_singleActiveTaskWithToken_backNavigationDisabled_removesWallpaper() {
     val task = setUpFreeformTask()
     val wallpaperToken = MockToken().token()
 
     desktopModeTaskRepository.wallpaperActivityToken = wallpaperToken
     val result = controller.handleRequest(Binder(), createTransition(task, type = TRANSIT_TO_BACK))
 
-    assertNotNull(result, "Should handle request")
-      // Should create remove wallpaper transaction
-      .assertRemoveAt(index = 0, wallpaperToken)
+    // Should create remove wallpaper transaction
+    assertNotNull(result, "Should handle request").assertRemoveAt(index = 0, wallpaperToken)
   }
 
   @Test
-  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_backTransition_multipleActiveTasksFlagDisabled_doesNotHandle() {
+  @DisableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_backTransition_multipleTasks_wallpaperDisabled_backNavDisabled_doesNotHandle() {
     val task1 = setUpFreeformTask()
     setUpFreeformTask()
 
@@ -1499,8 +1539,24 @@ class DesktopTasksControllerTest : ShellTestCase() {
   }
 
   @Test
+  @EnableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_backTransition_multipleTasks_wallpaperEnabled_backNavEnabled_removesTask() {
+    val task1 = setUpFreeformTask()
+    setUpFreeformTask()
+
+    desktopModeTaskRepository.wallpaperActivityToken = MockToken().token()
+    val result = controller.handleRequest(Binder(), createTransition(task1, type = TRANSIT_TO_BACK))
+
+    assertNotNull(result, "Should handle request").assertRemoveAt(index = 0, task1.token)
+  }
+
+  @Test
   @EnableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_backTransition_multipleActiveTasksFlagEnabled_doesNotHandle() {
+  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION)
+  fun handleRequest_backTransition_multipleTasks_backNavigationDisabled_doesNotHandle() {
     val task1 = setUpFreeformTask()
     setUpFreeformTask()
 
@@ -1511,8 +1567,28 @@ class DesktopTasksControllerTest : ShellTestCase() {
   }
 
   @Test
+  @EnableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_backTransition_multipleTasksSingleNonClosing_wallpaperEnabled_backNavEnabled_removesWallpaperAndTask() {
+    val task1 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
+    val task2 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
+    val wallpaperToken = MockToken().token()
+
+    desktopModeTaskRepository.wallpaperActivityToken = wallpaperToken
+    desktopModeTaskRepository.addClosingTask(displayId = DEFAULT_DISPLAY, taskId = task2.taskId)
+    val result = controller.handleRequest(Binder(), createTransition(task1, type = TRANSIT_TO_BACK))
+
+    // Should create remove wallpaper transaction
+    assertNotNull(result, "Should handle request").assertRemoveAt(index = 0, wallpaperToken)
+    result.assertRemoveAt(index = 1, task1.token)
+  }
+
+  @Test
   @EnableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_backTransition_multipleActiveTasksSingleNonClosing_handlesRequest() {
+  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION)
+  fun handleRequest_backTransition_multipleTasksSingleNonClosing_backNavigationDisabled_removesWallpaper() {
     val task1 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
     val task2 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
     val wallpaperToken = MockToken().token()
@@ -1521,14 +1597,33 @@ class DesktopTasksControllerTest : ShellTestCase() {
     desktopModeTaskRepository.addClosingTask(displayId = DEFAULT_DISPLAY, taskId = task2.taskId)
     val result = controller.handleRequest(Binder(), createTransition(task1, type = TRANSIT_TO_BACK))
 
-    assertNotNull(result, "Should handle request")
-      // Should create remove wallpaper transaction
-      .assertRemoveAt(index = 0, wallpaperToken)
+    // Should create remove wallpaper transaction
+    assertNotNull(result, "Should handle request").assertRemoveAt(index = 0, wallpaperToken)
+  }
+
+  @Test
+  @EnableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_backTransition_multipleTasksSingleNonMinimized_wallpaperEnabled_backNavEnabled_removesWallpaperAndTask() {
+    val task1 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
+    val task2 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
+    val wallpaperToken = MockToken().token()
+
+    desktopModeTaskRepository.wallpaperActivityToken = wallpaperToken
+    desktopModeTaskRepository.minimizeTask(displayId = DEFAULT_DISPLAY, taskId = task2.taskId)
+    val result = controller.handleRequest(Binder(), createTransition(task1, type = TRANSIT_TO_BACK))
+
+    // Should create remove wallpaper transaction
+    assertNotNull(result, "Should handle request").assertRemoveAt(index = 0, wallpaperToken)
+    result.assertRemoveAt(index = 1, task1.token)
   }
 
   @Test
   @EnableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_backTransition_multipleActiveTasksSingleNonMinimized_handlesRequest() {
+  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION)
+  fun handleRequest_backTransition_multipleTasksSingleNonMinimized_backNavigationDisabled_removesWallpaper() {
     val task1 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
     val task2 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
     val wallpaperToken = MockToken().token()
@@ -1537,14 +1632,36 @@ class DesktopTasksControllerTest : ShellTestCase() {
     desktopModeTaskRepository.minimizeTask(displayId = DEFAULT_DISPLAY, taskId = task2.taskId)
     val result = controller.handleRequest(Binder(), createTransition(task1, type = TRANSIT_TO_BACK))
 
-    assertNotNull(result, "Should handle request")
-      // Should create remove wallpaper transaction
-      .assertRemoveAt(index = 0, wallpaperToken)
+    // Should create remove wallpaper transaction
+    assertNotNull(result, "Should handle request").assertRemoveAt(index = 0, wallpaperToken)
   }
 
   @Test
-  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_closeTransition_singleActiveTaskNoTokenFlagDisabled_doesNotHandle() {
+  @EnableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_backTransition_nonMinimizadTask_wallpaperEnabled_backNavEnabled_removesWallpaper() {
+    val task1 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
+    val task2 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
+    val wallpaperToken = MockToken().token()
+
+    desktopModeTaskRepository.wallpaperActivityToken = wallpaperToken
+    desktopModeTaskRepository.minimizeTask(displayId = DEFAULT_DISPLAY, taskId = task2.taskId)
+    // Task is being minimized so mark it as not visible.
+    desktopModeTaskRepository
+      .updateVisibleFreeformTasks(displayId = DEFAULT_DISPLAY, task2.taskId, false)
+    val result = controller.handleRequest(Binder(), createTransition(task2, type = TRANSIT_TO_BACK))
+
+    assertNull(result, "Should not handle request")
+  }
+
+  @Test
+  @DisableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_closeTransition_singleActiveTaskNoToken_wallpaperDisabled_backNavDisabled_doesNotHandle() {
     val task = setUpFreeformTask()
 
     val result = controller.handleRequest(Binder(), createTransition(task, type = TRANSIT_CLOSE))
@@ -1553,8 +1670,22 @@ class DesktopTasksControllerTest : ShellTestCase() {
   }
 
   @Test
+  @EnableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_closeTransition_singleActiveTaskNoToken_wallpaperEnabled_backNavEnabled_removesTask() {
+    val task = setUpFreeformTask()
+
+    val result = controller.handleRequest(Binder(), createTransition(task, type = TRANSIT_CLOSE))
+
+    assertNotNull(result, "Should handle request").assertRemoveAt(index = 0, task.token)
+  }
+
+  @Test
   @EnableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_closeTransition_singleActiveTaskNoTokenFlagEnabled_doesNotHandle() {
+  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION)
+  fun handleRequest_closeTransition_singleActiveTaskNoToken_backNavigationDisabled_doesNotHandle() {
     val task = setUpFreeformTask()
 
     val result = controller.handleRequest(Binder(), createTransition(task, type = TRANSIT_CLOSE))
@@ -1563,8 +1694,11 @@ class DesktopTasksControllerTest : ShellTestCase() {
   }
 
   @Test
-  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_closeTransition_singleActiveTaskWithTokenFlagDisabled_doesNotHandle() {
+  @DisableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_closeTransition_singleActiveTaskWithToken_wallpaperDisabled_backNavDisabled_doesNotHandle() {
     val task = setUpFreeformTask()
 
     desktopModeTaskRepository.wallpaperActivityToken = MockToken().token()
@@ -1574,22 +1708,42 @@ class DesktopTasksControllerTest : ShellTestCase() {
   }
 
   @Test
+  @EnableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_closeTransition_singleActiveTaskWithToken_wallpaperEnabled_backNavEnabled_removesWallpaperAndTask() {
+    val task = setUpFreeformTask()
+    val wallpaperToken = MockToken().token()
+
+    desktopModeTaskRepository.wallpaperActivityToken = wallpaperToken
+    val result = controller.handleRequest(Binder(), createTransition(task, type = TRANSIT_CLOSE))
+
+    // Should create remove wallpaper transaction
+    assertNotNull(result, "Should handle request").assertRemoveAt(index = 0, wallpaperToken)
+    result.assertRemoveAt(index = 1, task.token)
+  }
+
+  @Test
   @EnableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_closeTransition_singleActiveTaskWithTokenFlagEnabled_handlesRequest() {
+  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION)
+  fun handleRequest_closeTransition_singleActiveTaskWithToken_backNavigationDisabled_removesWallpaper() {
     val task = setUpFreeformTask()
     val wallpaperToken = MockToken().token()
 
     desktopModeTaskRepository.wallpaperActivityToken = wallpaperToken
     val result = controller.handleRequest(Binder(), createTransition(task, type = TRANSIT_CLOSE))
 
-    assertNotNull(result, "Should handle request")
-      // Should create remove wallpaper transaction
-      .assertRemoveAt(index = 0, wallpaperToken)
+    // Should create remove wallpaper transaction
+    assertNotNull(result, "Should handle request").assertRemoveAt(index = 0, wallpaperToken)
   }
 
   @Test
-  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_closeTransition_multipleActiveTasksFlagDisabled_doesNotHandle() {
+  @DisableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_closeTransition_multipleTasks_wallpaperDisabled_backNavDisabled_doesNotHandle() {
     val task1 = setUpFreeformTask()
     setUpFreeformTask()
 
@@ -1600,8 +1754,25 @@ class DesktopTasksControllerTest : ShellTestCase() {
   }
 
   @Test
+  @EnableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_closeTransition_multipleTasks_wallpaperEnabled_backNavEnabled_removesTask() {
+    val task1 = setUpFreeformTask()
+    setUpFreeformTask()
+
+    desktopModeTaskRepository.wallpaperActivityToken = MockToken().token()
+    val result = controller.handleRequest(Binder(), createTransition(task1, type = TRANSIT_CLOSE))
+
+    assertNotNull(result, "Should handle request")
+    result.assertRemoveAt(index = 0, task1.token)
+  }
+
+  @Test
   @EnableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_closeTransition_multipleActiveTasksFlagEnabled_doesNotHandle() {
+  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION)
+  fun handleRequest_closeTransition_multipleTasksFlagEnabled_backNavigationDisabled_doesNotHandle() {
     val task1 = setUpFreeformTask()
     setUpFreeformTask()
 
@@ -1612,8 +1783,28 @@ class DesktopTasksControllerTest : ShellTestCase() {
   }
 
   @Test
+  @EnableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_closeTransition_multipleTasksSingleNonClosing_wallpaperEnabled_backNavEnabled_removesWallpaperAndTask() {
+    val task1 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
+    val task2 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
+    val wallpaperToken = MockToken().token()
+
+    desktopModeTaskRepository.wallpaperActivityToken = wallpaperToken
+    desktopModeTaskRepository.addClosingTask(displayId = DEFAULT_DISPLAY, taskId = task2.taskId)
+    val result = controller.handleRequest(Binder(), createTransition(task1, type = TRANSIT_CLOSE))
+
+    // Should create remove wallpaper transaction
+    assertNotNull(result, "Should handle request").assertRemoveAt(index = 0, wallpaperToken)
+    result.assertRemoveAt(index = 1, task1.token)
+  }
+
+  @Test
   @EnableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_closeTransition_multipleActiveTasksSingleNonClosing_handlesRequest() {
+  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION)
+  fun handleRequest_closeTransition_multipleTasksSingleNonClosing_backNavigationDisabled_removesWallpaper() {
     val task1 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
     val task2 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
     val wallpaperToken = MockToken().token()
@@ -1622,14 +1813,33 @@ class DesktopTasksControllerTest : ShellTestCase() {
     desktopModeTaskRepository.addClosingTask(displayId = DEFAULT_DISPLAY, taskId = task2.taskId)
     val result = controller.handleRequest(Binder(), createTransition(task1, type = TRANSIT_CLOSE))
 
-    assertNotNull(result, "Should handle request")
-      // Should create remove wallpaper transaction
-      .assertRemoveAt(index = 0, wallpaperToken)
+    // Should create remove wallpaper transaction
+    assertNotNull(result, "Should handle request").assertRemoveAt(index = 0, wallpaperToken)
+  }
+
+  @Test
+  @EnableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_closeTransition_multipleTasksOneNonMinimized_wallpaperEnabled_backNavEnabled_removesWallpaperAndTask() {
+    val task1 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
+    val task2 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
+    val wallpaperToken = MockToken().token()
+
+    desktopModeTaskRepository.wallpaperActivityToken = wallpaperToken
+    desktopModeTaskRepository.minimizeTask(displayId = DEFAULT_DISPLAY, taskId = task2.taskId)
+    val result = controller.handleRequest(Binder(), createTransition(task1, type = TRANSIT_CLOSE))
+
+    // Should create remove wallpaper transaction
+    assertNotNull(result, "Should handle request").assertRemoveAt(index = 0, wallpaperToken)
+    result.assertRemoveAt(index = 1, task1.token)
   }
 
   @Test
   @EnableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY)
-  fun handleRequest_closeTransition_multipleActiveTasksSingleNonMinimized_handlesRequest() {
+  @DisableFlags(Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION)
+  fun handleRequest_closeTransition_multipleTasksSingleNonMinimized_backNavigationDisabled_removesWallpaper() {
     val task1 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
     val task2 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
     val wallpaperToken = MockToken().token()
@@ -1638,9 +1848,28 @@ class DesktopTasksControllerTest : ShellTestCase() {
     desktopModeTaskRepository.minimizeTask(displayId = DEFAULT_DISPLAY, taskId = task2.taskId)
     val result = controller.handleRequest(Binder(), createTransition(task1, type = TRANSIT_CLOSE))
 
-    assertNotNull(result, "Should handle request")
-      // Should create remove wallpaper transaction
-      .assertRemoveAt(index = 0, wallpaperToken)
+    // Should create remove wallpaper transaction
+    assertNotNull(result, "Should handle request").assertRemoveAt(index = 0, wallpaperToken)
+  }
+
+  @Test
+  @EnableFlags(
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_WALLPAPER_ACTIVITY,
+    Flags.FLAG_ENABLE_DESKTOP_WINDOWING_BACK_NAVIGATION
+  )
+  fun handleRequest_closeTransition_minimizadTask_wallpaperEnabled_backNavEnabled_removesWallpaper() {
+    val task1 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
+    val task2 = setUpFreeformTask(displayId = DEFAULT_DISPLAY)
+    val wallpaperToken = MockToken().token()
+
+    desktopModeTaskRepository.wallpaperActivityToken = wallpaperToken
+    desktopModeTaskRepository.minimizeTask(displayId = DEFAULT_DISPLAY, taskId = task2.taskId)
+    // Task is being minimized so mark it as not visible.
+    desktopModeTaskRepository
+      .updateVisibleFreeformTasks(displayId = DEFAULT_DISPLAY, task2.taskId, false)
+    val result = controller.handleRequest(Binder(), createTransition(task2, type = TRANSIT_TO_BACK))
+
+    assertNull(result, "Should not handle request")
   }
 
   @Test