Add Physical Web OnInitialDisplay Uma

components/physical_web/webui/physical_web_base_message_handler.cc

Index: components/physical_web/webui/physical_web_base_message_handler.cc
diff --git a/components/physical_web/webui/physical_web_base_message_handler.cc b/components/physical_web/webui/physical_web_base_message_handler.cc
index fd7d4b61699b61603297fa8eb56292f549698776..68f033098f5e3ae2e858d41caaec7e45086f86cb 100644
--- a/components/physical_web/webui/physical_web_base_message_handler.cc
+++ b/components/physical_web/webui/physical_web_base_message_handler.cc
@@ -57,6 +57,9 @@ void PhysicalWebBaseMessageHandler::HandleRequestNearbyURLs(
 
   results.Set(physical_web_ui::kMetadata, metadata.release());
 
+  UMA_HISTOGRAM_EXACT_LINEAR("PhysicalWeb.TotalUrls.OnInitialDisplay",

[nyquist, 2017/02/28 19:47:23]

This seems to also be reported from PhysicalWebUma.java. Is that intentional?

[Ran, 2017/02/28 20:06:12]

Yes, this UMA in PhysicalWebUma.java was get called in
"chrome/browser/physicalweb/ListUrlsActivity.java". This file is no longer used
and so we should log it somewhere else.

It reminders us to do a clean up.

+                             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);