Ensure nearby URL count metric is properly initialized

components/omnibox/browser/physical_web_provider.h

Index: components/omnibox/browser/physical_web_provider.h
diff --git a/components/omnibox/browser/physical_web_provider.h b/components/omnibox/browser/physical_web_provider.h
index cab09c5c98296ab58b1616f2d42abdacdf80101c..54687a691dbe9ea31f0f73baa703e5e68b4852c0 100644
--- a/components/omnibox/browser/physical_web_provider.h
+++ b/components/omnibox/browser/physical_web_provider.h
@@ -47,6 +47,10 @@ class PhysicalWebProvider : public AutocompleteProvider {
                       HistoryURLProvider* history_url_provider);
   ~PhysicalWebProvider() override;
 
+  // Called when a new omnibox session is started. For the purposes of this
+  // provider, a session begins when the omnibox is initially focused.
+  void BeginOmniboxSession();
+
   // When the user has focused the omnibox but not yet entered any text (i.e.,
   // the Zero Suggest case), calling this method adds a separate match item to
   // |matches_| for each nearby URL in |metadata_list|, up to the maximum number
@@ -82,6 +86,10 @@ class PhysicalWebProvider : public AutocompleteProvider {
   // matches.

[Mark P, 2017/02/23 00:38:59]

Please say something about npos here and below.

[mattreynolds, 2017/02/23 02:03:07]

Done.

   size_t nearby_url_count_;
 
+  // The number of nearby Physical Web URLs when the omnibox input was last
+  // 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_;