Settings reset prompt: add UMA metrics reporting.

chrome/browser/safe_browsing/settings_reset_prompt/settings_reset_prompt_controller.h

 // Copyright 2017 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_SAFE_BROWSING_SETTINGS_RESET_PROMPT_SETTINGS_RESET_PROMPT_CONTROLLER_H_
 #define CHROME_BROWSER_SAFE_BROWSING_SETTINGS_RESET_PROMPT_SETTINGS_RESET_PROMPT_CONTROLLER_H_
 
 #include <memory>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/strings/string16.h"
+#include "base/time/time.h"
 #include "ui/gfx/range/range.h"
 
 class Browser;
 
 namespace safe_browsing {
 
 class SettingsResetPromptModel;
 
 // The |SettingsResetPromptController| class is responsible for providing the
 // text that will be displayed in the settings reset dialog. The controller's
@@ skipping 33 matching lines @@
   void InitMainText();
   // Function to be called sometime after |Accept()| or |Cancel()| has been
   // called to perform any final tasks (such as metrcis reporting) and delete
   // this object.
   void OnInteractionDone();
 
   std::unique_ptr<SettingsResetPromptModel> model_;
   base::string16 main_text_;
   gfx::Range main_text_url_range_;
 
+  // Used for metrics reporting.
+  base::Time time_dialog_shown_;
+
   DISALLOW_COPY_AND_ASSIGN(SettingsResetPromptController);
 };
 
 // Function to be called after startup in order to display the settings reset
 // prompt. The function will figure out if a prompt is needed, and if so, show
 // the dialog after a delay as determined by the |kSettingsResetPrompt|
 // feature parameters.
 void MaybeShowSettingsResetPromptWithDelay();
 
 }  // namespace safe_browsing
 
 #endif  // CHROME_BROWSER_SAFE_BROWSING_SETTINGS_RESET_PROMPT_SETTINGS_RESET_PROMPT_CONTROLLER_H_