Add UMA metrics for pop-up blocked page action on desktop

chrome/browser/content_settings/chrome_content_settings_utils.h

 // 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.
 
 #ifndef CHROME_BROWSER_CONTENT_SETTINGS_CHROME_CONTENT_SETTINGS_UTILS_H_
 #define CHROME_BROWSER_CONTENT_SETTINGS_CHROME_CONTENT_SETTINGS_UTILS_H_
 
 // Put utility functions only used by //chrome code here. If a function declared
 // here would be meaningfully shared with other platforms, consider moving it to
 // components/content_settings/core/browser/content_settings_utils.h.
@@ skipping 20 matching lines @@
   PLUGINS_ACTION_DISPLAYED_BUBBLE,
   PLUGINS_ACTION_CLICKED_RUN_ALL_PLUGINS_THIS_TIME,
   PLUGINS_ACTION_CLICKED_ALWAYS_ALLOW_PLUGINS_ON_ORIGIN,
   PLUGINS_ACTION_CLICKED_MANAGE_PLUGIN_BLOCKING,
   PLUGINS_ACTION_CLICKED_LEARN_MORE,
   PLUGINS_ACTION_COUNT
 };
 
 void RecordPluginsAction(PluginsAction action);
 
+// The different actions that a user can perform on the pop-up blocked page
+// action in the omnibox, The enum values back an UMA histogram, so they must be

[Nico, 2017/01/03 14:34:07]

don't capitalize after ,

Also, Use the same sentence structure as for the other enums in this file, i.e.
"UMA histogram for actions that a cuser can perform on the pop-up blocked page
action in the omnibox. The enum values correspond to histogram entries, so do
not remove any existing values." instead of what you have

+// treated as append-only.
+enum PopupsAction {
+  POPUPS_ACTION_DISPLAYED_BLOCKED_ICON_IN_OMNIBOX = 0,
+  POPUPS_ACTION_DISPLAYED_BUBBLE,
+  POPUPS_ACTION_SELECTED_ALWAYS_ALLOW_POPUPS_FROM,
+  POPUPS_ACTION_CLICKED_LIST_ITEM_CLICKED,
+  POPUPS_ACTION_CLICKED_MANAGE_POPUPS_BLOCKING,
+  POPUPS_ACTION_COUNT
+};
+
+void RecordPopupsAction(PopupsAction action);
+
 }  // namespace content_settings
 
 #endif  // CHROME_BROWSER_CONTENT_SETTINGS_CHROME_CONTENT_SETTINGS_UTILS_H_