Take 2 at implementing activeTab.

chrome/browser/extensions/active_tab_permission_manager.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_ACTIVE_TAB_PERMISSION_MANAGER_H_
+#define CHROME_BROWSER_EXTENSIONS_ACTIVE_TAB_PERMISSION_MANAGER_H_
+#pragma once
+
+#include <set>
+#include <string>
+
+#include "chrome/common/extensions/extension_set.h"
+#include "chrome/common/extensions/url_pattern_set.h"
+#include "content/public/browser/web_contents_observer.h"
+
+class TabContentsWrapper;
+
+namespace extensions {
+
+class Extension;
+
+// Responsible for granting and revoking tab-specific permissions to extensions
+// with the activeTab permission.
+class ActiveTabPermissionManager : public content::WebContentsObserver {
+ public:
+  explicit ActiveTabPermissionManager(TabContentsWrapper* tab_contents);
+  virtual ~ActiveTabPermissionManager();

[Aaron Boodman, 2012/06/06 01:03:13]

I think the destructor should be private; we only want to be deleted via the
WebContentsObserver interface.

+
+  // Grants tab-specific permissions to an extension for this tab until the
+  // next navigation or refresh, if the extension has the activeTab permission.
+  void Grant(const Extension* extension);
+
+ private:
+  // content::WebContentsObserver implementation.
+  virtual void DidCommitProvisionalLoadForFrame(
+      int64 frame_id,
+      bool is_main_frame,
+      const GURL& url,
+      content::PageTransition transition_type,
+      content::RenderViewHost* render_view_host) OVERRIDE;
+  virtual void WebContentsDestroyed(content::WebContents* web_contents)
+      OVERRIDE;
+
+  // Clears any granted tab-specific permissions for all extensions and
+  // notifies renderers.
+  void ClearActiveURLsAndNotify();
+
+  // Inserts a URL pattern giving access to the entire origin for |url|.
+  void InsertActiveURL(const GURL& url);
+
+  // Gets the current page ID.
+  int32 GetPageID();
+
+  // Our owning TabContentsWrapper.
+  TabContentsWrapper* tab_contents_;
+
+  // The URLPatternSet for frames that are active on the current page. This is
+  // cleared on navigation.
+  //
+  // Note that concerned code probably only cares about the origins of these
+  // URLs, but let them deal with that.
+  URLPatternSet active_urls_;
+
+  // Extensions with the activeTab permission that have been granted
+  // tab-specific permissions until the next navigation/refresh.
+  ExtensionSet granted_;
+
+  DISALLOW_COPY_AND_ASSIGN(ActiveTabPermissionManager);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_ACTIVE_TAB_PERMISSION_MANAGER_H_