Add Physical Web OnInitialDisplay Uma

components/physical_web/webui/physical_web_base_message_handler.cc

 // Copyright 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.
 
 #include "components/physical_web/webui/physical_web_base_message_handler.h"
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/user_metrics.h"
@@ skipping 39 matching lines @@
                              metadata_list_item.description);
     // Add the item index so when an item is selected, the index can be recorded
     // in a UMA histogram.
     metadata_item->SetInteger(physical_web_ui::kIndex, index);
     metadata->Append(std::move(metadata_item));
     ++index;
   }
 
   results.Set(physical_web_ui::kMetadata, metadata.release());
 
+  UMA_HISTOGRAM_EXACT_LINEAR("PhysicalWeb.TotalUrls.OnInitialDisplay",
+                             (int)metadata_list->size(), 50);
+
   // Pass the list of Physical Web URL metadata to the WebUI. A jstemplate will
   // create a list view with an item for each URL.
   CallJavaScriptFunction(physical_web_ui::kReturnNearbyUrls, results);
 }
 
 void PhysicalWebBaseMessageHandler::HandlePhysicalWebItemClicked(
     const base::ListValue* args) {
   int index = 0;
   if (!args->GetInteger(0, &index)) {
     DLOG(ERROR) << "Invalid selection index";
     return;
   }
 
   // Record the index of the selected item.
   UMA_HISTOGRAM_EXACT_LINEAR("PhysicalWeb.WebUI.ListViewUrlPosition", index,
                              50);
 
   // Count the number of selections.
   base::RecordAction(
       base::UserMetricsAction("PhysicalWeb.WebUI.ListViewUrlSelected"));
 }
 
 } //  namespace physical_web_ui