Move dispatching and sending of the last extension specific messages out of TabContents and Rende...

content/browser/tab_contents/tab_contents_observer.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/tab_contents/tab_contents_observer.h"
 
 #include "content/browser/renderer_host/render_view_host.h"
 #include "content/browser/tab_contents/tab_contents.h"
 
+TabContentsObserver::Registrar::Registrar(TabContentsObserver* observer)
+    : observer_(observer), tab_(NULL) {
+}
+
+TabContentsObserver::Registrar::~Registrar() {
+  if (tab_)
+    tab_->RemoveObserver(observer_);
+}
+
+void TabContentsObserver::Registrar::Observe(TabContents* tab) {
+  observer_->SetTabContents(tab);
+  if (tab_)
+    tab_->RemoveObserver(observer_);
+  tab_ = tab;
+  if (tab_)
+    tab_->AddObserver(observer_);
+}
+
 void TabContentsObserver::NavigateToPendingEntry() {
 }
 
 void TabContentsObserver::DidNavigateMainFramePostCommit(
     const NavigationController::LoadCommittedDetails& details,
     const ViewHostMsg_FrameNavigate_Params& params) {
 }
 
 void TabContentsObserver::DidNavigateAnyFramePostCommit(
     const NavigationController::LoadCommittedDetails& details,
     const ViewHostMsg_FrameNavigate_Params& params) {
 }
 
 void TabContentsObserver::OnProvisionalChangeToMainFrameUrl(const GURL& url) {
 }
 
 void TabContentsObserver::DidStartLoading() {
 }
 
 void TabContentsObserver::DidStopLoading() {
 }
 
 void TabContentsObserver::RenderViewGone() {
 }
 
 void TabContentsObserver::StopNavigation() {
 }
 
-TabContentsObserver::TabContentsObserver(TabContents* tab_contents)
-    : tab_contents_(tab_contents),
-      routing_id_(tab_contents->render_view_host()->routing_id()) {
+TabContentsObserver::TabContentsObserver(TabContents* tab_contents) {
+  SetTabContents(tab_contents);
   tab_contents_->AddObserver(this);
 }
 
+TabContentsObserver::TabContentsObserver()
+    : tab_contents_(NULL), routing_id_(MSG_ROUTING_NONE) {
+}
+
 TabContentsObserver::~TabContentsObserver() {
   if (tab_contents_)
     tab_contents_->RemoveObserver(this);
 }
 
 void TabContentsObserver::OnTabContentsDestroyed(TabContents* tab) {
 }
 
 bool TabContentsObserver::OnMessageReceived(const IPC::Message& message) {
   return false;
 }
 
 bool TabContentsObserver::Send(IPC::Message* message) {
   if (!tab_contents_ || !tab_contents_->render_view_host()) {
     delete message;
     return false;
   }
 
   return tab_contents_->render_view_host()->Send(message);
 }
 
+void TabContentsObserver::SetTabContents(TabContents* tab_contents) {
+  tab_contents_ = tab_contents;
+  if (tab_contents_)
+    routing_id_ = tab_contents->render_view_host()->routing_id();
+}
+
 void TabContentsObserver::TabContentsDestroyed() {
   // Do cleanup so that 'this' can safely be deleted from
   // OnTabContentsDestroyed.
   tab_contents_->RemoveObserver(this);
   TabContents* tab = tab_contents_;
   tab_contents_ = NULL;
   OnTabContentsDestroyed(tab);
 }