Make sure that a given app/extension requests only its own resources.

chrome/browser/extensions/api/api_resource_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_API_API_RESOURCE_MANAGER_H_
 #define CHROME_BROWSER_EXTENSIONS_API_API_RESOURCE_MANAGER_H_
 
 #include <map>
 
 #include "base/memory/linked_ptr.h"
@@ skipping 33 matching lines @@
     DCHECK(BrowserThread::CurrentlyOn(thread_id_));
     int id = GenerateId();
     if (id > 0) {
       linked_ptr<T> resource_ptr(api_resource);
       (*api_resource_map_)[id] = resource_ptr;
       return id;
     }
     return 0;
   }
 
-  void Remove(int api_resource_id) {
+  void Remove(const std::string& extension_id, int api_resource_id) {
     DCHECK(BrowserThread::CurrentlyOn(thread_id_));
-    api_resource_map_->erase(api_resource_id);
+    if (GetOwnedResource(extension_id, api_resource_id) != NULL) {
+      api_resource_map_->erase(api_resource_id);
+    }
   }
 
-  T* Get(int api_resource_id) {
+  T* Get(const std::string& extension_id, int api_resource_id) {
     DCHECK(BrowserThread::CurrentlyOn(thread_id_));
-    linked_ptr<T> ptr = (*api_resource_map_)[api_resource_id];
-    return ptr.get();
+    return GetOwnedResource(extension_id, api_resource_id);
   }
 
  private:
-  // TODO(miket): consider partitioning the ID space by extension ID to make it
-  // harder for extensions to peek into each others' resources.
   int GenerateId() {
     return next_id_++;
   }
 
+  T* GetOwnedResource(const std::string& extension_id,
+                      int api_resource_id) {
+    linked_ptr<T> ptr = (*api_resource_map_)[api_resource_id];
+    T* resource = ptr.get();
+    if (resource && extension_id == resource->owner_extension_id())
+      return resource;
+    return NULL;
+  }
+
   int next_id_;
   BrowserThread::ID thread_id_;
 
   // We need finer-grained control over the lifetime of this instance than RAII
   // can give us.
   std::map<int, linked_ptr<T> >* api_resource_map_;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_API_RESOURCE_MANAGER_H_