Implement a modal permission dialog on Android gated by a feature.

chrome/browser/permissions/permission_infobar_delegate.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_PERMISSIONS_PERMISSION_INFOBAR_DELEGATE_H_
 #define CHROME_BROWSER_PERMISSIONS_PERMISSION_INFOBAR_DELEGATE_H_
 
 #include <memory>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/macros.h"
 #include "chrome/browser/permissions/permission_util.h"
 #include "components/content_settings/core/common/content_settings_types.h"
 #include "components/infobars/core/confirm_infobar_delegate.h"
 #include "content/public/browser/permission_type.h"
 #include "url/gurl.h"
 
 namespace infobars {
 class InfoBar;
 }
 
 class InfoBarService;
 class Profile;
 
-// Base class for permission infobars, it implements the default behavior
-// so that the accept/deny buttons grant/deny the relevant permission.
-// A basic implementor only needs to implement the methods that
+// Base delegate class for permission prompts on Android. The default behavior
+// is that the accept/deny buttons grant/deny the relevant permission
+// respectively. A basic implementor only needs to implement the methods that
 // provide an icon and a message text to the infobar.
+//
+// By default, the user is presented with an infobar to make their choice. If
+// the experimental ModalPermissionPrompts feature is active, they will instead
+// see a modal dialog. Currently, this class is used for both; future
+// refactoring will be undertaken based on whether support for infobars is
+// retained following the modal prompt experiment.
 class PermissionInfoBarDelegate : public ConfirmInfoBarDelegate {
-
  public:
   using PermissionSetCallback = base::Callback<void(bool, PermissionAction)>;
 
   // Creates an infobar for |type|. The returned pointer is owned by
   // |infobar_service| and manages its own lifetime; callers must only use it
   // for calls to |infobar_service|.
   static infobars::InfoBar* Create(content::PermissionType type,
                                    InfoBarService* infobar_service,
                                    const GURL& requesting_frame,
                                    bool user_gesture,
                                    Profile* profile,
                                    const PermissionSetCallback& callback);
 
   ~PermissionInfoBarDelegate() override;
   virtual std::vector<int> content_settings() const;
 
   // Returns true if the infobar should display a toggle to allow users to
   // opt-out of persisting their accept/deny decision.
   bool ShouldShowPersistenceToggle() const;
 
   // Sets whether or not a decided permission should be persisted to content
   // settings.
   void set_persist(bool persist) { persist_ = persist; }
   bool persist() const { return persist_; }
 
   // ConfirmInfoBarDelegate:
+  bool Accept() override;
+  bool Cancel() override;
+  void InfoBarDismissed() override;
+  base::string16 GetButtonLabel(InfoBarButton button) const override;
   base::string16 GetMessageText() const override;
 
  protected:
   PermissionInfoBarDelegate(const GURL& requesting_origin,
                             content::PermissionType permission_type,
                             ContentSettingsType content_settings_type,
                             bool user_gesture,
                             Profile* profile,
                             const PermissionSetCallback& callback);
 
  private:
   // ConfirmInfoBarDelegate:
   Type GetInfoBarType() const override;
-  void InfoBarDismissed() override;
   PermissionInfoBarDelegate* AsPermissionInfoBarDelegate() override;
-  base::string16 GetButtonLabel(InfoBarButton button) const override;
-  bool Accept() override;
-  bool Cancel() override;
 
   virtual int GetMessageResourceId() const = 0;
   void SetPermission(bool update_content_setting, PermissionAction decision);
 
   GURL requesting_origin_;
   content::PermissionType permission_type_;
   ContentSettingsType content_settings_type_;
   Profile* const profile_;
   const PermissionSetCallback callback_;
   bool action_taken_;
   bool user_gesture_;
   bool persist_;
 
   DISALLOW_COPY_AND_ASSIGN(PermissionInfoBarDelegate);
 };
 
 // Implemented in platform-specific code.
 std::unique_ptr<infobars::InfoBar> CreatePermissionInfoBar(
     std::unique_ptr<PermissionInfoBarDelegate> delegate);
 
 #endif  // CHROME_BROWSER_PERMISSIONS_PERMISSION_INFOBAR_DELEGATE_H_