Revert of [Autofill] Migrate ContentPasswordManagerDriver<-->Password{Autofill,Generation}Agent IPCs to mojo.

components/password_manager/core/browser/password_autofill_manager.h

Index: components/password_manager/core/browser/password_autofill_manager.h
diff --git a/components/password_manager/core/browser/password_autofill_manager.h b/components/password_manager/core/browser/password_autofill_manager.h
index c1075c324df3d703ab1da6e3cb2a513e0fcb3a90..5bdaac74b617e4422eda40966b27e842cdee5a96 100644
--- a/components/password_manager/core/browser/password_autofill_manager.h
+++ b/components/password_manager/core/browser/password_autofill_manager.h
@@ -66,11 +66,6 @@
   // A public version of PreviewSuggestion(), only for use in tests.
   bool PreviewSuggestionForTest(int key, const base::string16& username);
 
-  // Only use in tests.
-  void set_autofill_client(autofill::AutofillClient* autofill_client) {
-    autofill_client_ = autofill_client;
-  }
-
  private:
   typedef std::map<int, autofill::PasswordFormFillData> LoginToPasswordInfoMap;
 
@@ -106,7 +101,7 @@
   // The driver that owns |this|.
   PasswordManagerDriver* password_manager_driver_;
 
-  autofill::AutofillClient* autofill_client_;  // weak
+  autofill::AutofillClient* const autofill_client_;  // weak
 
   base::WeakPtrFactory<PasswordAutofillManager> weak_ptr_factory_;