Merge "Fix the root task of secondary split screen could be overwritten." into rvc-dev

        // reparenting stack finished.

        // Keep the order from bottom to top.

        int numStacks = getStackCount();

        final boolean splitScreenActivated = toDisplayArea.isSplitScreenModeActivated();

        final ActivityStack rootStack = splitScreenActivated ? toDisplayArea

                .getTopStackInWindowingMode(WINDOWING_MODE_SPLIT_SCREEN_SECONDARY) : null;

        for (int stackNdx = 0; stackNdx < numStacks; stackNdx++) {

            final ActivityStack stack = getStackAt(stackNdx);

            // Always finish non-standard type stacks.

            if (destroyContentOnRemoval || !stack.isActivityTypeStandardOrUndefined()) {

                stack.finishAllActivitiesImmediately();

            } else {

                // If default display is in split-window mode, set windowing mode of the

                // stack to split-screen secondary. Otherwise, set the windowing mode to

                // undefined by default to let stack inherited the windowing mode from the

                // new display.

                final int windowingMode = toDisplayArea.isSplitScreenModeActivated()

                        ? WINDOWING_MODE_SPLIT_SCREEN_SECONDARY

                        : WINDOWING_MODE_UNDEFINED;

                stack.reparent(toDisplayArea, true /* onTop */);

                stack.setWindowingMode(windowingMode);

                // Reparent the stack to the root task of secondary-split-screen or display area.

                stack.reparent(stack.supportsSplitScreenWindowingMode() && rootStack != null

                        ? rootStack : toDisplayArea, POSITION_TOP);

                // Set the windowing mode to undefined by default to let the stack inherited the

                // windowing mode.

                stack.setWindowingMode(WINDOWING_MODE_UNDEFINED);

                lastReparentedStack = stack;

            }

            // Stacks may be removed from this display. Ensure each stack will be processed

            stackNdx -= numStacks - getStackCount();

            numStacks = getStackCount();

        }

        if (lastReparentedStack != null && splitScreenActivated) {

            if (!lastReparentedStack.supportsSplitScreenWindowingMode()) {

                mAtmService.getTaskChangeNotificationController()

                        .notifyActivityDismissingDockedStack();

                toDisplayArea.onSplitScreenModeDismissed(lastReparentedStack);

            } else if (rootStack != null) {

                // update focus

                rootStack.moveToFront("display-removed");

            }

        }

        mRemoved = true;

        return lastReparentedStack;