Re-land alexbost's experimental offscreenTabs API.

chrome/browser/extensions/extension_tab_util.h

 // 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_EXTENSIONS_EXTENSION_TAB_UTIL_H__
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_TAB_UTIL_H__
 #pragma once
 
 #include <string>
 
 class Browser;
+class Extension;
+class GURL;
 class Profile;
 class TabContents;
 class TabContentsWrapper;
 class TabStripModel;
 
 namespace base {
 class DictionaryValue;
 class ListValue;
 }
 
@@ skipping 33 matching lines @@
   static bool GetDefaultTab(Browser* browser,
                             TabContentsWrapper** contents,
                             int* tab_id);
   // Any out parameter (|browser|, |tab_strip|, |contents|, & |tab_index|) may
   // be NULL and will not be set within the function.
   static bool GetTabById(int tab_id, Profile* profile, bool incognito_enabled,
                          Browser** browser,
                          TabStripModel** tab_strip,
                          TabContentsWrapper** contents,
                          int* tab_index);
+
+  // Takes |url_string| and returns a GURL which is either valid and absolute
+  // or invalid. If |url_string| is not directly interpretable as a valid (it is
+  // likely a relative URL) an attempt is made to resolve it. |extension| is
+  // provided so it can be resolved relative to its extension base
+  // (chrome-extension://<id>/). Using the source frame url would be more
+  // correct, but because the api shipped with urls resolved relative to their
+  // extension base, we decided it wasn't worth breaking existing extensions to
+  // fix.
+  static GURL ResolvePossiblyRelativeURL(const std::string& url_string,
+                                         const Extension* extension);
+
+  // Returns true if |url| is used for testing crashes.
+  static bool IsCrashURL(const GURL& url);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_TAB_UTIL_H__