Ensure nearby URL count metric is properly initialized

components/omnibox/browser/physical_web_provider.h

 // Copyright (c) 2016 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 COMPONENTS_OMNIBOX_BROWSER_PHYSICAL_WEB_PROVIDER_H_
 #define COMPONENTS_OMNIBOX_BROWSER_PHYSICAL_WEB_PROVIDER_H_
 
 #include <vector>
 
 #include "base/macros.h"
@@ skipping 61 matching lines @@
   void AppendOverflowItem(int additional_url_count,
                           int relevance,
                           const base::string16& title);
 
   AutocompleteProviderClient* client_;
 
   // Used for efficiency when creating the verbatim match. Can be null.
   HistoryURLProvider* history_url_provider_;
 
   // The number of nearby Physical Web URLs when the provider last constructed
-  // matches.
+  // matches. Initialized to string::npos.
   size_t nearby_url_count_;
 
+  // The number of nearby Physical Web URLs when the omnibox input was last
+  // focused. Initialized to string::npos.
+  // This value is set when the omnibox is focused and recorded when the user
+  // selects an omnibox suggestion. If the value is still string::npos when the
+  // user makes a selection, it indicates the omnibox was never focused.
+  size_t nearby_url_count_at_focus_;
+
   // If true, provide suggestions when the user has focused the omnibox but has
   // not typed anything.
   bool zero_suggest_enabled_;
 
   // If true, provide suggestions when the user has entered a query into the
   // omnibox.
   bool after_typing_enabled_;
 
   // The base relevance score for Physical Web URL suggestions when the user has
   // not typed anything into the omnibox.
@@ skipping 10 matching lines @@
 
   // Set to true if at least one suggestion was created since the last time the
   // omnibox was focused, even if the suggestion could not be displayed due to
   // a field trial.
   bool had_physical_web_suggestions_at_focus_or_later_;
 
   DISALLOW_COPY_AND_ASSIGN(PhysicalWebProvider);
 };
 
 #endif  // COMPONENTS_OMNIBOX_BROWSER_PHYSICAL_WEB_PROVIDER_H_