Remove unused field ScriptExecutor:on_terminate_prompt_

on_terminate_prompt_ is left over from a previous refactoring. It was
checked but never actually set. This change removes it completely.

Bug: 981363
Change-Id: I8ca8142b6bfe66f0e36d186b8559a31fcbf92313
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1735151Reviewed-by: Mathias Carlen <mcarlen@chromium.org>
Commit-Queue: Stephane Zermatten <szermatt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#683963}

components/autofill_assistant/browser/script_executor.cc

@@ -300,10 +300,6 @@ void ScriptExecutor::Prompt(
 }
 
 void ScriptExecutor::CancelPrompt() {
-  // Delete on_terminate_prompt_ if necessary, without running.
-  if (on_terminate_prompt_)
-    std::move(on_terminate_prompt_);
-
   delegate_->SetUserActions(nullptr);
   CleanUpAfterPrompt();
 }

components/autofill_assistant/browser/script_executor.h

@@ -373,10 +373,6 @@ class ScriptExecutor : public ActionDelegate,
   TopPadding last_focused_element_top_padding_;
   std::unique_ptr<ElementAreaProto> touchable_element_area_;
 
-  // Callback set by Prompt(). This is called when the prompt is terminated
-  // without selecting any chips. nullptr unless showing a prompt.
-  base::OnceCallback<void()> on_terminate_prompt_;
-
   // Steps towards the requirements for calling |on_expected_navigation_done_|
   // to be fulfilled.
   enum class ExpectedNavigationStep {