Add GetCurrentRoutes() to MediaRouter API, ensure dialog has routes at init

chrome/browser/ui/webui/media_router/media_router_ui.cc

 // Copyright 2015 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 "chrome/browser/ui/webui/media_router/media_router_ui.h"
 
 #include <algorithm>
 #include <string>
 #include <unordered_map>
 #include <utility>
@@ skipping 146 matching lines @@
     }
   }
 
   callback_.Run(routes_for_display, joinable_route_ids_for_display);
 }
 
 MediaRouterUI::MediaRouterUI(content::WebUI* web_ui)
     : ConstrainedWebDialogUI(web_ui),
       handler_(new MediaRouterWebUIMessageHandler(this)),
       ui_initialized_(false),
+      initial_routes_received_(false),
       current_route_request_id_(-1),
       route_request_counter_(0),
       initiator_(nullptr),
       router_(nullptr),
       weak_factory_(this) {
   // Create a WebUIDataSource containing the chrome://media-router page's
   // content.
   std::unique_ptr<content::WebUIDataSource> html_source(
       content::WebUIDataSource::Create(chrome::kChromeUIMediaRouterHost));
 
@@ skipping 347 matching lines @@
 void MediaRouterUI::SetIssue(const Issue* issue) {
   if (ui_initialized_) handler_->UpdateIssue(issue);
 }
 
 void MediaRouterUI::OnRoutesUpdated(
     const std::vector<MediaRoute>& routes,
     const std::vector<MediaRoute::Id>& joinable_route_ids) {
   routes_ = routes;
   joinable_route_ids_ = joinable_route_ids;
 
+  if (!initial_routes_received_)
+    initial_routes_received_ = true;
+
   std::unordered_map<MediaSource::Id, MediaCastMode> available_source_map;
   for (const auto& cast_mode : cast_modes_) {
     for (const auto& source :
          query_result_manager_->GetSourcesForCastMode(cast_mode)) {
       available_source_map.insert(std::make_pair(source.id(), cast_mode));
     }
   }
 
   current_cast_modes_.clear();
   for (const auto& route : routes) {
@@ skipping 121 matching lines @@
                                           Profile::FromWebUI(web_ui())))
              : TruncateHost(GetHostFromURL(gurl));
 }
 
 const std::string& MediaRouterUI::GetRouteProviderExtensionId() const {
   // TODO(crbug.com/597778): remove reference to MediaRouterMojoImpl
   return static_cast<MediaRouterMojoImpl*>(router_)
       ->media_route_provider_extension_id();
 }
 
+const std::vector<MediaRoute>& MediaRouterUI::GetRoutes() {
+  if (!initial_routes_received_) {
+    // OnRoutesUpdated() updates |routes_| with routes for display.
+    routes_observer_->OnRoutesUpdated(router_->GetCurrentRoutes(),

[imcheng, 2016/11/30 19:54:06]

This feels a bit strange. You are calling the observer so that it will call back
to MRUI to update |routes_|. It looks like what you can do instead is to call
GetCurrentRoutes() in InitCommon() to populate |routes_|. Then you don't need
this method and |initial_routes_received_|.

[mark a. foltz, 2016/11/30 23:52:10]

Will this be the same routes list as UIMediaRoutesObserver?

[takumif, 2016/12/01 00:51:13]

UIMediaRoutesObserver::OnRoutesUpdated() filters out non-display routes. We
could avoid passing the routes through UIMediaRoutesObserver by moving the
filtering functionality to MediaRouterUI::OnRoutesUpdated().

+                                      std::vector<MediaRoute::Id>());
+  }
+  return routes_;
+}
+
 void MediaRouterUI::SetUIInitializationTimer(const base::Time& start_time) {
   DCHECK(!start_time.is_null());
   start_time_ = start_time;
 }
 
 void MediaRouterUI::OnUIInitiallyLoaded() {
   if (!start_time_.is_null()) {
     MediaRouterMetrics::RecordMediaRouterDialogPaint(
         base::Time::Now() - start_time_);
   }
 }
 
 void MediaRouterUI::OnUIInitialDataReceived() {
   if (!start_time_.is_null()) {
     MediaRouterMetrics::RecordMediaRouterDialogLoaded(
         base::Time::Now() - start_time_);
     start_time_ = base::Time();
   }
 }
 
 void MediaRouterUI::UpdateMaxDialogHeight(int height) {
   handler_->UpdateMaxDialogHeight(height);
 }
 
 }  // namespace media_router