Use stricter type checking in UMA_HISTOGRAM_ENUMERATION

chrome/browser/chromeos/login/screens/reset_screen.cc

 // Copyright (c) 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.
 
 #include "chrome/browser/chromeos/login/screens/reset_screen.h"
 
 #include "base/command_line.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/values.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 54 matching lines @@
 ResetScreen::~ResetScreen() {
   if (view_)
     view_->Unbind();
   DBusThreadManager::Get()->GetUpdateEngineClient()->RemoveObserver(this);
 }
 
 void ResetScreen::Show() {
   if (view_)
     view_->Show();
 
-  int dialog_type = -1;  // used by UMA metrics.
+  reset::DialogViewType dialog_type =
+      reset::DIALOG_VIEW_TYPE_SIZE;  // used by UMA metrics.
 
   ContextEditor context_editor = GetContextEditor();
 
   bool restart_required = !base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kFirstExecAfterBoot);
   if (restart_required) {
     context_editor.SetInteger(kContextKeyScreenState, STATE_RESTART_REQUIRED);
     dialog_type = reset::DIALOG_SHORTCUT_RESTART_REQUIRED;
   } else {
     context_editor.SetInteger(kContextKeyScreenState, STATE_POWERWASH_PROPOSAL);
   }
 
   // Set availability of Rollback feature.
   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kDisableRollbackOption)) {
     context_editor.SetBoolean(kContextKeyIsRollbackAvailable, false);
     dialog_type = reset::DIALOG_SHORTCUT_OFFERING_ROLLBACK_UNAVAILABLE;
   } else {
     chromeos::DBusThreadManager::Get()->GetUpdateEngineClient()->
         CanRollbackCheck(base::Bind(&ResetScreen::OnRollbackCheck,
         weak_ptr_factory_.GetWeakPtr()));
   }
 
-  if (dialog_type >= 0) {
+  if (dialog_type < reset::DIALOG_VIEW_TYPE_SIZE) {
     UMA_HISTOGRAM_ENUMERATION("Reset.ChromeOS.PowerwashDialogShown",
                               dialog_type,
                               reset::DIALOG_VIEW_TYPE_SIZE);
   }
 
   PrefService* prefs = g_browser_process->local_state();
   prefs->SetBoolean(prefs::kFactoryResetRequested, false);
   prefs->CommitPendingWrite();
 }
 
@@ skipping 87 matching lines @@
       !context_.GetBoolean(kContextKeyIsRollbackChecked)) {
     UMA_HISTOGRAM_ENUMERATION(
         "Reset.ChromeOS.PowerwashDialogShown",
         reset::DIALOG_SHORTCUT_OFFERING_ROLLBACK_AVAILABLE,
         reset::DIALOG_VIEW_TYPE_SIZE);
     GetContextEditor().SetBoolean(kContextKeyIsRollbackChecked, true);
   }
 }
 
 void ResetScreen::OnShowConfirm() {
-  int dialog_type = context_.GetBoolean(kContextKeyIsRollbackChecked) ?
-      reset::DIALOG_SHORTCUT_CONFIRMING_POWERWASH_AND_ROLLBACK :
-      reset::DIALOG_SHORTCUT_CONFIRMING_POWERWASH_ONLY;
+  reset::DialogViewType dialog_type =
+      context_.GetBoolean(kContextKeyIsRollbackChecked)
+          ? reset::DIALOG_SHORTCUT_CONFIRMING_POWERWASH_AND_ROLLBACK
+          : reset::DIALOG_SHORTCUT_CONFIRMING_POWERWASH_ONLY;
   UMA_HISTOGRAM_ENUMERATION(
       "Reset.ChromeOS.PowerwashDialogShown",
       dialog_type,
       reset::DIALOG_VIEW_TYPE_SIZE);
 
   GetContextEditor().SetBoolean(kContextKeyIsConfirmational, true);
 }
 
 void ResetScreen::OnLearnMore() {
 #if defined(OFFICIAL_BUILD)
@@ skipping 22 matching lines @@
     get_base_screen_delegate()->ShowErrorScreen();
   } else if (status.status ==
       UpdateEngineClient::UPDATE_STATUS_UPDATED_NEED_REBOOT) {
     DBusThreadManager::Get()->GetPowerManagerClient()->RequestRestart();
   }
 }
 
 // Invoked from call to CanRollbackCheck upon completion of the DBus call.
 void ResetScreen::OnRollbackCheck(bool can_rollback) {
   VLOG(1) << "Callback from CanRollbackCheck, result " << can_rollback;
-  int dialog_type = can_rollback ?
-      reset::DIALOG_SHORTCUT_OFFERING_ROLLBACK_AVAILABLE :
-      reset::DIALOG_SHORTCUT_OFFERING_ROLLBACK_UNAVAILABLE;
+  reset::DialogViewType dialog_type =
+      can_rollback ? reset::DIALOG_SHORTCUT_OFFERING_ROLLBACK_AVAILABLE
+                   : reset::DIALOG_SHORTCUT_OFFERING_ROLLBACK_UNAVAILABLE;
   UMA_HISTOGRAM_ENUMERATION("Reset.ChromeOS.PowerwashDialogShown",
                             dialog_type,
                             reset::DIALOG_VIEW_TYPE_SIZE);
 
   GetContextEditor().SetBoolean(kContextKeyIsRollbackAvailable, can_rollback);
 }
 
 ErrorScreen* ResetScreen::GetErrorScreen() {
   return get_base_screen_delegate()->GetErrorScreen();
 }
 
 }  // namespace chromeos