Add core plumbing for Instant Extended work

chrome/browser/ui/search/search_model.h

Index: chrome/browser/ui/search/search_model.h
diff --git a/chrome/browser/ui/search/search_model.h b/chrome/browser/ui/search/search_model.h
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+++ b/chrome/browser/ui/search/search_model.h
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+// 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.
+
+#ifndef CHROME_BROWSER_UI_SEARCH_SEARCH_MODEL_H_
+#define CHROME_BROWSER_UI_SEARCH_SEARCH_MODEL_H_
+#pragma once
+
+#include "base/basictypes.h"
+#include "base/observer_list.h"
+#include "chrome/browser/ui/search/search_types.h"
+#include "third_party/skia/include/core/SkColor.h"
+#include "ui/gfx/rect.h"
+
+class TabContents;
+
+namespace content {
+class WebContents;
+}
+
+namespace chrome {
+namespace search {
+
+class SearchModelObserver;
+
+// An observable model for UI components that care about search model state
+// changes.
+class SearchModel {
+ public:
+  explicit SearchModel(TabContents* contents);
+  ~SearchModel();
+
+  // Change the mode.  Change notifications are sent to observers.  An animated
+  // transition may be requested.
+  void SetMode(const Mode& mode);
+
+  // Get the active mode.
+  const Mode& mode() const { return mode_; }
+
+  // Change the mode to |to_mode| only if |from_mode| is the active mode.
+  void MaybeChangeMode(Mode::Type from_mode, Mode::Type to_mode);
+
+  // Add and remove observers.
+  void AddObserver(SearchModelObserver* observer);
+  void RemoveObserver(SearchModelObserver* observer);
+
+  // This can be NULL if this is the browser model and it's accessed during
+  // startup or shutdown.
+  const TabContents* tab_contents() const {
+    return contents_;
+  }
+
+  void set_tab_contents(TabContents* contents) {
+    contents_ = contents;
+  }
+
+ private:
+  // The display mode of UI elements such as the toolbar, the tab strip, etc.
+  Mode mode_;
+
+  // Weak. Used to access current profile to determine incognito status.
+  TabContents* contents_;
+
+  // Observers.
+  ObserverList<SearchModelObserver> observers_;
+
+  DISALLOW_COPY_AND_ASSIGN(SearchModel);
+};
+
+}  // namespace search
+}  // namespace chrome
+
+#endif  // CHROME_BROWSER_UI_SEARCH_SEARCH_MODEL_H_