Move guest lifetime management to chrome

chrome/browser/guest_view/web_view/web_view_guest.cc

Index: chrome/browser/guest_view/web_view/web_view_guest.cc
diff --git a/chrome/browser/guest_view/web_view/web_view_guest.cc b/chrome/browser/guest_view/web_view/web_view_guest.cc
index 981e16626e6b37000aa396729277e901b29a915c..7c23cc160c50f7705a06df11168ab0116587dfb6 100644
--- a/chrome/browser/guest_view/web_view/web_view_guest.cc
+++ b/chrome/browser/guest_view/web_view/web_view_guest.cc
@@ -177,7 +177,6 @@ WebViewGuest::WebViewGuest(int guest_instance_id,
    :  GuestView<WebViewGuest>(guest_instance_id,
                               guest_web_contents,
                               embedder_extension_id),
-      WebContentsObserver(guest_web_contents),
       script_executor_(new extensions::ScriptExecutor(guest_web_contents,
                                                       &script_observers_)),
       pending_context_menu_request_id_(0),
@@ -883,6 +882,7 @@ void WebViewGuest::WebContentsDestroyed() {
       embedder_extension_id(), view_instance_id()));
 
   RemoveWebViewFromExtensionRendererState(web_contents());
+  GuestViewBase::WebContentsDestroyed();
 }
 
 void WebViewGuest::UserAgentOverrideSet(const std::string& user_agent) {