Replace OnPageTranslate Obsever by a responder of delegate.

components/translate/core/browser/translate_infobar_delegate.cc

Index: components/translate/core/browser/translate_infobar_delegate.cc
diff --git a/components/translate/core/browser/translate_infobar_delegate.cc b/components/translate/core/browser/translate_infobar_delegate.cc
index 1ca24c8e7dda38048ce612f9df423a68aebf6bba..e6df58584d2b5e929ebf1fc29f145a4a0ce53358 100644
--- a/components/translate/core/browser/translate_infobar_delegate.cc
+++ b/components/translate/core/browser/translate_infobar_delegate.cc
@@ -101,12 +101,18 @@ void TranslateInfoBarDelegate::Create(
     old_infobar = infobar_manager->infobar_at(i);
     old_delegate = old_infobar->delegate()->AsTranslateInfoBarDelegate();
     if (old_delegate) {
-      if (!replace_existing_infobar || IsCompactUIEnabled())
+      if (!replace_existing_infobar)
         return;
       break;
     }
   }
 
+  // Try to reuse existing translate infobar delegate.
+  if (old_delegate && old_delegate->responder_) {
+    old_delegate->responder_->ActionOnStep(step, error_type);
+    return;
+  }
+
   // Add the new delegate.
   TranslateClient* translate_client = translate_manager->translate_client();
   std::unique_ptr<infobars::InfoBar> infobar(translate_client->CreateInfoBar(
@@ -124,6 +130,10 @@ bool TranslateInfoBarDelegate::IsCompactUIEnabled() {
   return base::FeatureList::IsEnabled(kTranslateCompactUI);
 }
 
+void TranslateInfoBarDelegate::SetResponder(Responder* responder) {
+  responder_ = responder;
+}
+
 void TranslateInfoBarDelegate::UpdateOriginalLanguage(
     const std::string& language_code) {
   ui_delegate_.UpdateOriginalLanguage(language_code);