Implement SearchTabHelperDelegate.

chrome/browser/ui/search/search_tab_helper_delegate.h

+// Copyright 2014 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_TAB_HELPER_DELEGATE_H_
+#define CHROME_BROWSER_UI_SEARCH_SEARCH_TAB_HELPER_DELEGATE_H_
+
+#include <vector>
+
+#include "chrome/common/instant_types.h"
+#include "ui/base/window_open_disposition.h"
+
+namespace content {
+class WebContents;
+}
+
+class GURL;
+class OmniboxView;
+
+// Objects implement this interface to get notified about changes in the
+// SearchTabHelper and to provide necessary functionality.
+class SearchTabHelperDelegate {

[Jered, 2014/04/04 22:39:27]

Why not make this abstract? A possible answer would be to make tests easier, but
I don't see any in this CL?

[kmadhusu, 2014/04/07 21:44:15]

In future, TabAndroid will implement this interface. Most of these functions
will have an empty implementation for TabAndroid. That's why I didn't make this
abstract. 

+ public:
+  // Navigates the page to |url|. Usually used by the page to navigate to
+  // privileged destinations (e.g. chrome:// URLs) or to navigate to URLs that
+  // are hidden from the page using Restricted IDs (rid in the API).
+  virtual void NavigateToURL(const GURL& url,
+                             WindowOpenDisposition disposition,
+                             content::WebContents* source_contents);
+
+  // Invoked when the |web_contents| no longer supports Instant.
+  virtual void OnWebContentsInstantSupportDisabled(
+      const content::WebContents* web_contents);
+
+  // Removes recommended URLs if a matching URL is already open in the Browser,
+  // if the Most Visited Tile Placement experiment is enabled, and the client is
+  // in the experiment group.
+  virtual void RemoveMostVisitedItemsMatchingOpenTabs(
+      std::vector<InstantMostVisitedItem>* items);
+
+  // Returns the OmniboxView or NULL if not available.
+  virtual OmniboxView* GetOmniboxView();
+
+ protected:
+  virtual ~SearchTabHelperDelegate();
+};
+
+#endif  // CHROME_BROWSER_UI_SEARCH_SEARCH_TAB_HELPER_DELEGATE_H_