[Media Router] Return NotFoundError on dialog exit if appropriate

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 <utility>
 
@@ skipping 185 matching lines @@
 }
 
 MediaRouterUI::~MediaRouterUI() {
   if (issues_observer_) issues_observer_->UnregisterObserver();
 
   if (query_result_manager_.get()) query_result_manager_->RemoveObserver(this);
   if (presentation_service_delegate_.get())
     presentation_service_delegate_->RemoveDefaultPresentationRequestObserver(
         this);
   // If |create_session_request_| still exists, then it means presentation route
-  // request was never attempted.
+  // request was never attempted. This could be because the dialog defaults to

[imcheng, 2016/06/29 17:28:03]

nit: I would just leave out the part about defaulting to mirroring.

[btolsch, 2016/06/30 07:29:16]

Done.

+  // mirroring when no devices support the presentation url.
   if (create_session_request_) {
-    create_session_request_->InvokeErrorCallback(content::PresentationError(
-        content::PRESENTATION_ERROR_SESSION_REQUEST_CANCELLED,
-        "Dialog closed."));
+    bool presentation_sinks_available = std::any_of(
+        sinks_.begin(), sinks_.end(), [](const MediaSinkWithCastModes& sink) {
+          return sink.cast_modes.find(MediaCastMode::DEFAULT) !=

[imcheng, 2016/06/29 17:28:03]

nit: return sink.cast_modes.ContainsValue(MediaCastMode::DEFAULT);

[btolsch, 2016/06/30 07:29:16]

Done.

[imcheng, 2016/06/30 18:24:46]

Thanks. Apologies for suggesting the wrong syntax :)

+                 sink.cast_modes.end();
+        });
+    if (presentation_sinks_available) {
+      create_session_request_->InvokeErrorCallback(content::PresentationError(
+          content::PRESENTATION_ERROR_SESSION_REQUEST_CANCELLED,
+          "Dialog closed."));
+    } else {
+      create_session_request_->InvokeErrorCallback(content::PresentationError(
+          content::PRESENTATION_ERROR_NO_AVAILABLE_SCREENS,
+          "No screens found."));
+    }
   }
 }
 
 void MediaRouterUI::InitWithDefaultMediaSource(
     const base::WeakPtr<PresentationServiceDelegateImpl>& delegate) {
   DCHECK(delegate);
   DCHECK(!presentation_service_delegate_);
   DCHECK(!query_result_manager_.get());
 
   presentation_service_delegate_ = delegate;
@@ skipping 463 matching lines @@
         base::Time::Now() - start_time_);
     start_time_ = base::Time();
   }
 }
 
 void MediaRouterUI::UpdateMaxDialogHeight(int height) {
   handler_->UpdateMaxDialogHeight(height);
 }
 
 }  // namespace media_router