Show the Cast toolbar icon ephemerally when Cast is in use

chrome/browser/ui/toolbar/media_router_action.h

Index: chrome/browser/ui/toolbar/media_router_action.h
diff --git a/chrome/browser/ui/toolbar/media_router_action.h b/chrome/browser/ui/toolbar/media_router_action.h
index ace06a32f18e0cdfe7f86ea861e907c9cdadf917..ee48ac81ff58b1d8d575ce710c6191d11b4c0c3b 100644
--- a/chrome/browser/ui/toolbar/media_router_action.h
+++ b/chrome/browser/ui/toolbar/media_router_action.h
@@ -13,6 +13,7 @@
 #include "chrome/browser/ui/toolbar/media_router_contextual_menu.h"
 #include "chrome/browser/ui/toolbar/toolbar_action_view_controller.h"
 #include "chrome/browser/ui/toolbar/toolbar_actions_bar.h"
+#include "chrome/browser/ui/toolbar/toolbar_actions_bar_observer.h"
 #include "ui/gfx/vector_icons_public.h"
 
 class Browser;
@@ -28,7 +29,8 @@ class MediaRouterDialogControllerImpl;
 class MediaRouterAction : public ToolbarActionViewController,
                           public media_router::IssuesObserver,
                           public media_router::MediaRoutesObserver,
-                          public TabStripModelObserver {
+                          public TabStripModelObserver,
+                          public ToolbarActionsBarObserver {
  public:
   MediaRouterAction(Browser* browser, ToolbarActionsBar* toolbar_actions_bar);
   ~MediaRouterAction() override;
@@ -67,9 +69,19 @@ class MediaRouterAction : public ToolbarActionViewController,
                         int index,
                         int reason) override;
 
+  // ToolbarActionsBarObserver:
+  void OnToolbarActionsBarAnimationEnded() override;
+
   void OnPopupHidden();
   void OnPopupShown();
 
+  // Toggle the "Always show icon" option.
+  void ToggleVisibilityPreference();
+
+ protected:
+  // For accessing from tests.
+  base::WeakPtr<MediaRouterAction> GetWeakPtr();
+
  private:
   // Called when a new browser window is opened, the user switches tabs in the
   // browser window, or when |delegate_| is swapped out to be non-null and has
@@ -92,6 +104,11 @@ class MediaRouterAction : public ToolbarActionViewController,
   // updates |current_icon_|.
   void MaybeUpdateIcon();
 
+  void MaybeRemoveAction();
+
+  // Returns whether the "Always show icon" option is checked.
+  bool ShouldAlwaysShowIcon();
+
   gfx::VectorIconId GetCurrentIcon() const;
 
   // The current icon to show. This is updated based on the current issues and
@@ -117,6 +134,8 @@ class MediaRouterAction : public ToolbarActionViewController,
 
   ScopedObserver<TabStripModel, TabStripModelObserver>
       tab_strip_model_observer_;
+  ScopedObserver<ToolbarActionsBar, ToolbarActionsBarObserver>
+      toolbar_actions_bar_observer_;
 
   base::WeakPtrFactory<MediaRouterAction> weak_ptr_factory_;