edit: Add default '(deleted)' string if message has zero length.

Author: yadav-rahul

app/src/main/java/com/zulip/android/activities/MessageListFragment.java

@@ -419,7 +419,8 @@ public void onClick(View view) {
                     progress.setCancelable(false);
                     progress.setMessage(app.getString(R.string.editing_message));
                     progress.show();
-                    final String editedMessageContent = dialogMessageEditText.getText().toString();
+                    final String editedMessageContent =
+                            dialogMessageEditText.getText().toString().length() == 0 ? getString(R.string.default_delete_text) : dialogMessageEditText.getText().toString();
 
                     app.getZulipServices()
                             .editMessage(String.valueOf(message.getID()), editedMessageContent)

app/src/main/res/values/strings.xml

@@ -137,4 +137,5 @@
     </plurals>
     <string name="maximum_time_limit_error">Maximum time limit exceeded</string>
     <string name="editing_message_disabled">Editing message is disabled</string>
+    <string name="default_delete_text">(deleted)</string>
 </resources>