Replace OnPageTranslate Obsever by a responder of delegate.

components/translate/core/browser/translate_infobar_delegate.h

Index: components/translate/core/browser/translate_infobar_delegate.h
diff --git a/components/translate/core/browser/translate_infobar_delegate.h b/components/translate/core/browser/translate_infobar_delegate.h
index 6a8a77b94dbb3de095bcfff8d57f2ea1170a0868..cb4a7bc4c002d5b10f99137629fe1d2a025ac689 100644
--- a/components/translate/core/browser/translate_infobar_delegate.h
+++ b/components/translate/core/browser/translate_infobar_delegate.h
@@ -37,6 +37,19 @@ class TranslateManager;
 
 class TranslateInfoBarDelegate : public infobars::InfoBarDelegate {
  public:
+  // A responder to handle different translate steps' UI changes.
+  class Responder {
+   public:
+    // Handles UI changes on the translate step given.
+    virtual void ActionOnStep(translate::TranslateStep step,
+                              TranslateErrors::Type error_type){};
+    // Return whether user declined translate service.
+    virtual bool Declined();
+
+   protected:
+    virtual ~Responder() {}
+  };
+
   static const size_t kNoIndex;
 
   ~TranslateInfoBarDelegate() override;
@@ -182,6 +195,9 @@ class TranslateInfoBarDelegate : public infobars::InfoBarDelegate {
   // May return NULL if the driver has been destroyed.
   TranslateDriver* GetTranslateDriver();
 
+  // Set a responder.
+  void SetResponder(Responder* responder);
+
  protected:
   TranslateInfoBarDelegate(
       const base::WeakPtr<TranslateManager>& translate_manager,
@@ -219,6 +235,10 @@ class TranslateInfoBarDelegate : public infobars::InfoBarDelegate {
   // (due to language detection, preferences...)
   bool triggered_from_menu_;
 
+  // A responder to handle front-end changes on different steps.
+  // It's only used when we try to reuse the existing UI.
+  Responder* responder_;

[napper, 2017/05/19 00:17:50]

Responder* const responder_;

[Leo, 2017/05/19 03:30:24]

We can talk this offline.

+
   DISALLOW_COPY_AND_ASSIGN(TranslateInfoBarDelegate);
 };