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..0b2dc486974a44eda07792ed93deba23502952d3 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"
@@ -31,6 +32,7 @@ class Profile;
 class StackedPanelCollection;
 
 namespace content {
+class RenderViewHost;

[Avi (use Gerrit), 2015/05/11 19:05:00]

If this is only used for the WCO override, can't you rely on the header file to
declare it?

[lazyboy, 2015/05/11 19:22:53]

Yes, thanks.
Done.

 class WebContents;
 struct NativeWebKeyboardEvent;
 }
@@ -53,6 +55,7 @@ class WindowController;
 class Panel : public ui::BaseWindow,
               public CommandUpdaterDelegate,
               public content::NotificationObserver,
+              public content::WebContentsObserver,
               public extensions::ExtensionRegistryObserver {
  public:
   enum ExpansionState {
@@ -147,6 +150,10 @@ 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,