Do not allow GuestViewManager to (re)use an instance ID that was already removed.

chrome/browser/guest_view/guest_view_manager.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_GUEST_VIEW_GUEST_VIEW_MANAGER_H_
 #define CHROME_BROWSER_GUEST_VIEW_GUEST_VIEW_MANAGER_H_
 
 #include <map>
 
+#include "base/gtest_prod_util.h"
 #include "base/lazy_instance.h"
 #include "base/macros.h"
 #include "content/public/browser/browser_plugin_guest_manager.h"
 #include "content/public/browser/site_instance.h"
 #include "content/public/browser/web_contents.h"
 
 class GuestViewBase;
 class GuestWebContentsObserver;
 class GURL;
 
@@ skipping 29 matching lines @@
   virtual void MaybeGetGuestByInstanceIDOrKill(
       int guest_instance_id,
       int embedder_render_process_id,
       const GuestByInstanceIDCallback& callback) OVERRIDE;
   virtual bool ForEachGuest(content::WebContents* embedder_web_contents,
                             const GuestCallback& callback) OVERRIDE;
 
  private:
   friend class GuestViewBase;
   friend class GuestWebContentsObserver;
+  friend class TestGuestViewManager;
+  FRIEND_TEST_ALL_PREFIXES(GuestViewManagerTest, AddRemove);
 
-  void AddGuest(int guest_instance_id,
+  // Returns true if adding the instance was successful.
+  bool AddGuest(int guest_instance_id,
                 content::WebContents* guest_web_contents);
 
   void RemoveGuest(int guest_instance_id);
 
   void AddRenderProcessHostID(int render_process_host_id);
 
   content::SiteInstance* GetGuestSiteInstance(
       const GURL& guest_site);
 
   content::WebContents* GetGuestByInstanceID(
@@ skipping 11 matching lines @@
                                      GuestViewBase* guest);
 
   // Counts RenderProcessHost IDs of GuestViewBases.
   std::multiset<int> render_process_host_id_multiset_;
 
   // Contains guests' WebContents, mapping from their instance ids.
   typedef std::map<int, content::WebContents*> GuestInstanceMap;
   GuestInstanceMap guest_web_contents_by_instance_id_;
 
   int current_instance_id_;
+
+  // Any instance ID whose number not greater than this was removed via
+  // RemoveGuest.
+  // This is used so that we don't have store all removed instance IDs in
+  // |removed_instance_ids_|.
+  int last_instance_id_removed_;
+  // The remaining instance IDs that are greater than
+  // |last_instance_id_removed_| are kept here.
+  std::set<int> removed_instance_ids_;
+
   content::BrowserContext* context_;
 
   DISALLOW_COPY_AND_ASSIGN(GuestViewManager);
 };
 
 #endif  // CHROME_BROWSER_GUEST_VIEW_GUEST_VIEW_MANAGER_H_