[mob][photos] unselect all selected items on system back navigation

mobile/lib/ui/tabs/home_widget.dart

@@ -1,5 +1,5 @@
 import 'dart:async';
-import 'dart:io';
+import "dart:io";
 
 import 'package:flutter/material.dart';
 import 'package:flutter/scheduler.dart';
@@ -7,9 +7,9 @@ import 'package:flutter/services.dart';
 import "package:flutter_animate/flutter_animate.dart";
 import "package:flutter_local_notifications/flutter_local_notifications.dart";
 import 'package:logging/logging.dart';
-import 'package:media_extension/media_extension_action_types.dart';
+import "package:media_extension/media_extension_action_types.dart";
 import 'package:modal_bottom_sheet/modal_bottom_sheet.dart';
-import 'package:move_to_background/move_to_background.dart';
+import "package:move_to_background/move_to_background.dart";
 import 'package:photos/core/configuration.dart';
 import 'package:photos/core/event_bus.dart';
 import 'package:photos/ente_theme_data.dart';
@@ -320,6 +320,10 @@ class _HomeWidgetState extends State<HomeWidget> {
         onPopInvoked: (didPop) async {
           if (didPop) return;
           if (_selectedTabIndex == 0) {
+            if (_selectedFiles.files.isNotEmpty) {
+              _selectedFiles.clearAll();
+              return;
+            }
             if (isSettingsOpen) {
               Navigator.pop(context);
             } else if (Platform.isAndroid && action == IntentAction.main) {

mobile/lib/ui/viewer/actions/file_selection_overlay_bar.dart

@@ -54,6 +54,23 @@ class _FileSelectionOverlayBarState extends State<FileSelectionOverlayBar> {
       '$runtimeType building with ${widget.selectedFiles.files.length}',
     );
 
+    return widget.galleryType == GalleryType.homepage
+        ? _body()
+        : PopScope(
+            canPop: false,
+            onPopInvoked: (didPop) {
+              if (!didPop) {
+                if (widget.selectedFiles.files.isEmpty) {
+                  Navigator.of(context).pop();
+                }
+                widget.selectedFiles.clearAll();
+              }
+            },
+            child: _body(),
+          );
+  }
+
+  Widget _body() {
     return ValueListenableBuilder(
       valueListenable: _hasSelectedFilesNotifier,
       builder: (context, value, child) {