Fix number of buckets in Tabs.ScrubDistance UMA histogram.

chrome/browser/ui/views/ash/tab_scrubber.cc

 // Copyright (c) 2013 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/ui/views/ash/tab_scrubber.h"
 
 #include "ash/shell.h"
 #include "ash/wm/window_util.h"
 #include "base/metrics/histogram.h"
 #include "chrome/browser/chrome_notification_types.h"
@@ skipping 256 matching lines @@
     BrowserView* browser_view =
         BrowserView::GetBrowserViewForNativeWindow(
             browser_->window()->GetNativeWindow());
     TabStrip* tab_strip = browser_view->tabstrip();
     if (activate && highlighted_tab_ != -1) {
       Tab* tab = tab_strip->tab_at(highlighted_tab_);
       tab->hover_controller()->HideImmediately();
       int distance =
           std::abs(
               highlighted_tab_ - browser_->tab_strip_model()->active_index());
-      UMA_HISTOGRAM_CUSTOM_COUNTS("Tabs.ScrubDistance", distance, 0, 20, 20);
+      UMA_HISTOGRAM_CUSTOM_COUNTS("Tabs.ScrubDistance", distance, 0, 20, 21);
       browser_->tab_strip_model()->ActivateTabAt(highlighted_tab_, true);
     }
     tab_strip->RemoveObserver(this);
   }
   swipe_x_ = -1;
   swipe_y_ = -1;
   scrubbing_ = false;
   highlighted_tab_ = -1;
 }