Update Physical Web WebUI to show new results automatically

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"
 #include "components/physical_web/data_source/physical_web_data_source.h"
 #include "components/physical_web/webui/physical_web_ui_constants.h"
 
 namespace physical_web_ui {
 
-PhysicalWebBaseMessageHandler::PhysicalWebBaseMessageHandler() {}
+PhysicalWebBaseMessageHandler::PhysicalWebBaseMessageHandler()
+    : data_source_(nullptr) {}
 
-PhysicalWebBaseMessageHandler::~PhysicalWebBaseMessageHandler() = default;
+PhysicalWebBaseMessageHandler::~PhysicalWebBaseMessageHandler() {
+  if (data_source_)
+    data_source_->UnregisterListener(this);
+}
+
+void PhysicalWebBaseMessageHandler::OnFound(const GURL& url) {
+  PushNearbyURLs();
+}
+
+void PhysicalWebBaseMessageHandler::OnLost(const GURL& url) {
+  // do nothing
+}
+
+void PhysicalWebBaseMessageHandler::OnDistanceChanged(
+    const GURL& url,
+    double distance_estimate) {
+  // do nothing
+}
 
 void PhysicalWebBaseMessageHandler::RegisterMessages() {
   RegisterMessageCallback(
-      kRequestNearbyUrls,
+      kPhysicalWebPageLoaded,
       base::BindRepeating(
-          &PhysicalWebBaseMessageHandler::HandleRequestNearbyURLs,
+          &PhysicalWebBaseMessageHandler::HandlePhysicalWebPageLoaded,
           base::Unretained(this)));
-  RegisterMessageCallback(kPhysicalWebItemClicked,
+
+  RegisterMessageCallback(
+      kPhysicalWebItemClicked,
       base::BindRepeating(
           &PhysicalWebBaseMessageHandler::HandlePhysicalWebItemClicked,
           base::Unretained(this)));
+
+  data_source_ = GetPhysicalWebDataSource();
+  if (data_source_)
+    data_source_->RegisterListener(this, physical_web::OPPORTUNISTIC);
 }
 
-void PhysicalWebBaseMessageHandler::HandleRequestNearbyURLs(
-    const base::ListValue* args) {
+void PhysicalWebBaseMessageHandler::PushNearbyURLs() {
   base::DictionaryValue results;
 
   std::unique_ptr<physical_web::MetadataList> metadata_list =
       GetPhysicalWebDataSource()->GetMetadataList();
 
+  // Append new metadata at the end of the list.
+  for (const auto& metadata_list_item : *metadata_list) {
+    const std::string& group_id = metadata_list_item.group_id;
+    if (metadata_map_.find(group_id) == metadata_map_.end()) {
+      ordered_group_ids_.push_back(group_id);
+      metadata_map_.insert(std::make_pair(group_id, metadata_list_item));
+    }
+  }
+
   auto metadata = base::MakeUnique<base::ListValue>();
   int index = 0;
-  for (const auto& metadata_list_item : *metadata_list) {
+  for (const auto& group_id : ordered_group_ids_) {
+    auto metadata_list_item = metadata_map_[group_id];
     auto metadata_item = base::MakeUnique<base::DictionaryValue>();
     metadata_item->SetString(physical_web_ui::kResolvedUrl,
                              metadata_list_item.resolved_url.spec());
     metadata_item->SetString(physical_web_ui::kPageInfoIcon,
                              metadata_list_item.icon_url.spec());
     metadata_item->SetString(physical_web_ui::kPageInfoTitle,
                              metadata_list_item.title);
     metadata_item->SetString(physical_web_ui::kPageInfoDescription,
                              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);
+  CallJavaScriptFunction(physical_web_ui::kPushNearbyUrls, results);
+}
+
+void PhysicalWebBaseMessageHandler::HandlePhysicalWebPageLoaded(
+    const base::ListValue* args) {
+  PushNearbyURLs();
+  UMA_HISTOGRAM_EXACT_LINEAR("PhysicalWeb.TotalUrls.OnInitialDisplay",
+                             (int)ordered_group_ids_.size(), 50);
 }
 
 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
+}  //  namespace physical_web_ui