[Media Router] Add a presentation id to MediaRoute mapping in the MR

chrome/browser/media/router/media_router_base.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/media/router/media_router_base.h"
 
 #include "base/bind.h"
 #include "base/guid.h"
 #include "base/memory/ptr_util.h"
 #include "base/stl_util.h"
@@ skipping 20 matching lines @@
     incognito_route_ids.clear();
     // TODO(crbug.com/611486): Have the MRPM pass a list of joinable route ids
     // via |joinable_route_ids|, and check here if it is non-empty.
     has_route = !routes.empty();
     for (const auto& route : routes) {
       if (route.is_incognito())
         incognito_route_ids.push_back(route.media_route_id());
     }
   }
 
+  const MediaRoute* GetPresentationRoute(
+      const std::string& presentation_id) const {
+    for (const auto& route : current_routes) {
+      if (route.presentation_id().has_value() &&

[mark a. foltz, 2017/03/10 00:56:28]

I think .has_value() is optional here.

[zhaobin, 2017/03/10 01:51:11]

Done.

+          (*route.presentation_id()) == presentation_id) {

[mark a. foltz, 2017/03/10 00:56:28]

In other code I have used .value() explicitly to retrieve the value (so I don't
have to remember what * does) but I don't feel strongly either way.

[zhaobin, 2017/03/10 01:51:11]

Done.

+        return &route;
+      }
+    }
+
+    return nullptr;
+  }
+
   bool has_route;
   std::vector<MediaRoute> current_routes;
   std::vector<MediaRoute::Id> incognito_route_ids;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(InternalMediaRoutesObserver);
 };
 
 MediaRouterBase::~MediaRouterBase() {
   CHECK(!internal_routes_observer_);
@@ skipping 18 matching lines @@
 
 void MediaRouterBase::OnIncognitoProfileShutdown() {
   for (const auto& route_id : internal_routes_observer_->incognito_route_ids)
     TerminateRoute(route_id);
 }
 
 std::vector<MediaRoute> MediaRouterBase::GetCurrentRoutes() const {
   return internal_routes_observer_->current_routes;
 }
 
+const MediaRoute* MediaRouterBase::GetPresentationRoute(
+    const std::string& presentation_id) const {
+  DCHECK(internal_routes_observer_);
+  return internal_routes_observer_->GetPresentationRoute(presentation_id);
+}
+
 MediaRouterBase::MediaRouterBase() : initialized_(false) {}
 
 // static
 std::string MediaRouterBase::CreatePresentationId() {
   return "mr_" + base::GenerateGUID();
 }
 
 void MediaRouterBase::NotifyPresentationConnectionStateChange(
     const MediaRoute::Id& route_id,
     content::PresentationConnectionState state) {
@@ skipping 43 matching lines @@
   }
 }
 
 void MediaRouterBase::Shutdown() {
   // The observer calls virtual methods on MediaRouter; it must be destroyed
   // outside of the dtor
   internal_routes_observer_.reset();
 }
 
 }  // namespace media_router