[Media Router] Force DEFAULT cast mode when starting presentations from content.

chrome/browser/ui/webui/media_router/media_router_webui_message_handler.h

 // 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.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_WEBUI_MESSAGE_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_WEBUI_MESSAGE_HANDLER_H_
 
 #include <unordered_map>
 #include <vector>
 
 #include "base/macros.h"
+#include "base/optional.h"
 #include "chrome/browser/ui/webui/media_router/media_cast_mode.h"
 #include "chrome/browser/ui/webui/media_router/media_sink_with_cast_modes.h"
 #include "chrome/common/media_router/issue.h"
 #include "chrome/common/media_router/media_status.h"
 #include "components/signin/core/browser/account_info.h"
 #include "content/public/browser/web_ui_message_handler.h"
 #include "ui/gfx/geometry/size.h"
 
 namespace base {
 class DictionaryValue;
@@ skipping 15 matching lines @@
  public:
   explicit MediaRouterWebUIMessageHandler(MediaRouterUI* media_router_ui);
   ~MediaRouterWebUIMessageHandler() override;
 
   // Methods to update the status displayed by the dialog.
   void UpdateSinks(const std::vector<MediaSinkWithCastModes>& sinks);
   void UpdateRoutes(const std::vector<MediaRoute>& routes,
                     const std::vector<MediaRoute::Id>& joinable_route_ids,
                     const std::unordered_map<MediaRoute::Id, MediaCastMode>&
                         current_cast_modes);
-  void UpdateCastModes(const CastModeSet& cast_modes,
-                       const std::string& source_host);
+  // Overridden in tests.
+  virtual void UpdateCastModes(const CastModeSet& cast_modes,
+                               const std::string& source_host,
+                               base::Optional<MediaCastMode> forced_cast_mode);
   void OnCreateRouteResponseReceived(const MediaSink::Id& sink_id,
                                      const MediaRoute* route);
   void ReturnSearchResult(const std::string& sink_id);
 
   void UpdateIssue(const Issue& issue);
   void ClearIssue();
 
   // Updates the maximum dialog height to allow the WebUI properly scale when
   // the browser window changes.
   void UpdateMaxDialogHeight(int height);
@@ skipping 97 matching lines @@
   base::Optional<MediaStatus> current_media_status_;
 
   MediaRouterUI* media_router_ui_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaRouterWebUIMessageHandler);
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_UI_WEBUI_MEDIA_ROUTER_MEDIA_ROUTER_WEBUI_MESSAGE_HANDLER_H_