[Extensions] Migrate ExtensionInstallPrompt::Delegate to be a callback

chrome/browser/extensions/navigation_observer.h

Index: chrome/browser/extensions/navigation_observer.h
diff --git a/chrome/browser/extensions/navigation_observer.h b/chrome/browser/extensions/navigation_observer.h
index eae903c583e079061eaf12a240540648cabe0abe..fb2ca9860c4ffc7f38133c925069f00d8d78cb3b 100644
--- a/chrome/browser/extensions/navigation_observer.h
+++ b/chrome/browser/extensions/navigation_observer.h
@@ -10,6 +10,7 @@
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "chrome/browser/extensions/extension_install_prompt.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
@@ -26,8 +27,7 @@ namespace extensions {
 // navigates into an extension that has been disabled due to a permission
 // increase, it prompts the user to accept the new permissions and re-enables
 // the extension.
-class NavigationObserver : public ExtensionInstallPrompt::Delegate,
-                           public content::NotificationObserver {
+class NavigationObserver : public content::NotificationObserver {
  public:
   explicit NavigationObserver(Profile* profile);
   ~NavigationObserver() override;
@@ -47,9 +47,7 @@ class NavigationObserver : public ExtensionInstallPrompt::Delegate,
   void PromptToEnableExtensionIfNecessary(
       content::NavigationController* nav_controller);
 
-  // ExtensionInstallPrompt::Delegate callbacks used for the permissions prompt.
-  void InstallUIProceed() override;
-  void InstallUIAbort(bool user_initiated) override;
+  void OnInstallPromptDone(ExtensionInstallPrompt::Result result);
 
   content::NotificationRegistrar registrar_;
 
@@ -65,6 +63,8 @@ class NavigationObserver : public ExtensionInstallPrompt::Delegate,
   // The extension ids we've already prompted the user about.
   std::set<std::string> prompted_extensions_;
 
+  base::WeakPtrFactory<NavigationObserver> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(NavigationObserver);
 };