Add core plumbing for Instant Extended work

chrome/browser/ui/search/search_delegate.cc

+// Copyright (c) 2012 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 "chrome/browser/ui/search/search_delegate.h"
+
+#include "chrome/browser/ui/search/search_model.h"
+#include "chrome/browser/ui/search/search_tab_helper.h"
+#include "chrome/browser/ui/tab_contents/tab_contents.h"
+
+namespace chrome {
+namespace search {
+
+SearchDelegate::SearchDelegate(SearchModel* browser_model)
+    : browser_model_(browser_model),
+      tab_model_(NULL) {
+}
+
+SearchDelegate::~SearchDelegate() {
+  DCHECK(!tab_model_) << "All tabs should have been deactivated or closed.";
+}
+
+void SearchDelegate::ModeChanged(const Mode& mode) {
+  browser_model_->SetMode(mode);
+}
+
+void SearchDelegate::OnTabActivated(TabContents* contents) {
+  if (tab_model_)
+    tab_model_->RemoveObserver(this);
+  tab_model_ = contents->search_tab_helper()->model();
+  DCHECK_EQ(tab_model_->tab_contents(), contents);
+  browser_model_->set_tab_contents(contents);
+  browser_model_->SetMode(tab_model_->mode());
+  tab_model_->AddObserver(this);
+}
+
+void SearchDelegate::OnTabDeactivated(TabContents* contents) {
+  StopObserveringTab(contents);
+}
+
+void SearchDelegate::OnTabDetached(TabContents* contents) {
+  StopObserveringTab(contents);
+}
+
+void SearchDelegate::StopObserveringTab(
+    TabContents* contents) {
+  if (contents->search_tab_helper()->model() == tab_model_) {
+    tab_model_->RemoveObserver(this);
+    browser_model_->set_tab_contents(NULL);
+    tab_model_ = NULL;
+  }
+}
+
+}  // namespace search
+}  // namespace chrome