Make UMA_HISTOGRAM_ENUMERATION work with scoped enums.

chrome/browser/chromeos/login/users/avatar/user_image_manager_impl.cc

 // 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.
 
 #include "chrome/browser/chromeos/login/users/avatar/user_image_manager_impl.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 630 matching lines @@
   job_->LoadImage(base::FilePath(image_path), image_index, image_url);
 }
 
 void UserImageManagerImpl::UserLoggedIn(bool user_is_new,
                                         bool user_is_local) {
   const user_manager::User* user = GetUser();
   if (user_is_new) {
     if (!user_is_local)
       SetInitialUserImage();
   } else {
-    UMA_HISTOGRAM_ENUMERATION("UserImage.LoggedIn",
-                              ImageIndexToHistogramIndex(user->image_index()),
-                              default_user_image::kHistogramImagesCount);
+    UMA_HISTOGRAM_EXACT_LINEAR("UserImage.LoggedIn",

[wychen, 2017/03/27 20:08:56]

Ditto.

+                               ImageIndexToHistogramIndex(user->image_index()),
+                               default_user_image::kHistogramImagesCount);
   }
 
   // Reset the downloaded profile image as a new user logged in.
   downloaded_profile_image_ = gfx::ImageSkia();
   profile_image_url_ = GURL();
   profile_image_requested_ = false;
 
   user_image_sync_observer_.reset();
   TryToCreateImageSyncObserver();
 }
@@ skipping 358 matching lines @@
 }
 
 bool UserImageManagerImpl::IsUserLoggedInAndHasGaiaAccount() const {
   const user_manager::User* user = GetUser();
   if (!user)
     return false;
   return user->is_logged_in() && user->HasGaiaAccount();
 }
 
 }  // namespace chromeos