Add script trigger content size changed on android

Signed-off-by: dab246 <tdvu@linagora.com>
(cherry picked from commit c39e932b634d164d75c0cf1cac35c27be04d8e1b)

core/lib/presentation/utils/html_transformer/html_utils.dart

@@ -6,6 +6,7 @@ import 'package:flutter/material.dart';
 class HtmlUtils {
 
   static const scrollEventJSChannelName = 'ScrollEventListener';
+  static const contentSizeChangedEventJSChannelName = 'ContentSizeChangedEventListener';
 
   static const runScriptsHandleScrollEvent = '''
     let contentElement = document.getElementsByClassName('tmail-content')[0];
@@ -61,6 +62,16 @@ class HtmlUtils {
     }
   ''';
 
+  static const scriptsHandleContentSizeChanged = '''
+    <script>
+      const bodyResizeObserver = new ResizeObserver(entries => {
+        window.flutter_inappwebview.callHandler('$contentSizeChangedEventJSChannelName', '');
+      })
+      
+      bodyResizeObserver.observe(document.body)
+    </script>
+  ''';
+
   static String customCssStyleHtmlEditor({TextDirection direction = TextDirection.ltr}) {
     if (PlatformInfo.isWeb) {
       return '''