Remove NOTIFICATION_RENDER_VIEW_HOST_CHANGED.

chrome/browser/ui/panels/panel.h

Index: chrome/browser/ui/panels/panel.h
diff --git a/chrome/browser/ui/panels/panel.h b/chrome/browser/ui/panels/panel.h
index fa511d7b1b457b2f401509e7303e0ccaf5147687..877b08c3e52c56d0232e2dc09083534287d26905 100644
--- a/chrome/browser/ui/panels/panel.h
+++ b/chrome/browser/ui/panels/panel.h
@@ -17,6 +17,7 @@
 #include "components/sessions/session_id.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
+#include "content/public/browser/web_contents_observer.h"
 #include "extensions/browser/extension_registry_observer.h"
 #include "ui/base/base_window.h"
 #include "ui/gfx/geometry/rect.h"
@@ -53,6 +54,7 @@ class WindowController;
 class Panel : public ui::BaseWindow,
               public CommandUpdaterDelegate,
               public content::NotificationObserver,
+              public content::WebContentsObserver,
               public extensions::ExtensionRegistryObserver {
  public:
   enum ExpansionState {
@@ -147,6 +149,10 @@ class Panel : public ui::BaseWindow,
                const content::NotificationSource& source,
                const content::NotificationDetails& details) override;
 
+  // content::WebContentsObserver overrides.
+  void RenderViewHostChanged(content::RenderViewHost* old_host,
+                             content::RenderViewHost* new_host) override;
+
   //  extensions::ExtensionRegistryObserver.
   void OnExtensionUnloaded(
       content::BrowserContext* browser_context,