Move guest lifetime management to chrome

chrome/browser/guest_view/web_view/web_view_guest.h

Index: chrome/browser/guest_view/web_view/web_view_guest.h
diff --git a/chrome/browser/guest_view/web_view/web_view_guest.h b/chrome/browser/guest_view/web_view/web_view_guest.h
index c88de6ccc7362c4f61f68a147c6fa914f3fb219d..a40900cd67e9cde9569b1b1a719964191b1c7994 100644
--- a/chrome/browser/guest_view/web_view/web_view_guest.h
+++ b/chrome/browser/guest_view/web_view/web_view_guest.h
@@ -16,7 +16,6 @@
 #include "chrome/common/extensions/api/webview.h"
 #include "content/public/browser/javascript_dialog_manager.h"
 #include "content/public/browser/notification_registrar.h"
-#include "content/public/browser/web_contents_observer.h"
 #include "third_party/WebKit/public/web/WebFindOptions.h"
 
 #if defined(OS_CHROMEOS)
@@ -44,8 +43,7 @@ class SimpleMenuModel;
 // or through the use of the New Window API, when a new window is attached to
 // a particular <webview>.
 class WebViewGuest : public GuestView<WebViewGuest>,
-                     public content::NotificationObserver,
-                     public content::WebContentsObserver {
+                     public content::NotificationObserver {
  public:
   WebViewGuest(int guest_instance_id,
                content::WebContents* guest_web_contents,