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/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+#include "content/public/browser/web_contents_observer.h"
+
+class TabContents;
+
+namespace extensions {
+
+class Extension;
+
+// Responsible for granting and revoking tab-specific permissions to extensions
+// with the activeTab permission.
+class ActiveTabPermissionManager : public content::WebContentsObserver,
+                                   public content::NotificationObserver {
+ public:
+  explicit ActiveTabPermissionManager(TabContents* tab_contents);
+  virtual ~ActiveTabPermissionManager();
+
+  // If |extension| has the activeTab permission, grants tab-specific
+  // permissions to it until the next page navigation or refresh.
+  void MaybeGrant(const Extension* extension);
+
+  // 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)

[Aaron Boodman, 2012/06/08 05:31:30]

Add a blank line here. Also, can this be private?

[not at google - send to devlin, 2012/06/12 20:40:51]

I usually see methods bunched together like this when they're just a bunch of
overrides to an interface. But ok.

This one can be private but the other can't, I'm calling it from a test
(unfortunately, but I don't see any other way) to fake creating frames on this
tab.

Anyway, updated.

+      OVERRIDE;
+
+ private:
+  // content::NotificationObserver implementation.
+  virtual void Observe(int type,
+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) 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 tab's id.
+  int tab_id();
+
+  // Gets the current page id.
+  int32 GetPageID();
+
+  // Our owning TabContents.
+  TabContents* 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_;
+
+  // Listen to extension unloaded notifications.
+  content::NotificationRegistrar registrar_;
+
+  DISALLOW_COPY_AND_ASSIGN(ActiveTabPermissionManager);
+};
+
+}  // namespace extensions
+
+#endif  // CHROME_BROWSER_EXTENSIONS_ACTIVE_TAB_PERMISSION_MANAGER_H_