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..3363da4dd15b996f8bf3dbc714001027cf7b5426 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 +86,14 @@ class PhysicalWebProvider : public AutocompleteProvider {
   // matches.
   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_;

[Mark P, 2017/02/22 06:25:39]

Can you use npos and test for it explicitly rather than having a second field to
detect validity?

[mattreynolds, 2017/02/22 20:53:55]

Sure, done.

+
+  // The nearby URL count is invalid if the omnibox was not focused during the
+  // current omnibox session. Invalid URL counts should not be recorded.
+  bool nearby_url_count_at_focus_valid_;
+
   // If true, provide suggestions when the user has focused the omnibox but has
   // not typed anything.
   bool zero_suggest_enabled_;