[Extensions] Handle some funny cases in script injection

extensions/renderer/script_injection_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 EXTENSIONS_RENDERER_SCRIPT_INJECTION_MANAGER_H_
 #define EXTENSIONS_RENDERER_SCRIPT_INJECTION_MANAGER_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 81 matching lines @@
   // Handle the GrantInjectionPermission extension message.
   void HandlePermitScriptInjection(int64 request_id);
 
   // Extensions metadata, owned by Dispatcher (which owns this object).
   const ExtensionSet* extensions_;
 
   // The map of active web frames to their corresponding statuses. The
   // RunLocation of the frame corresponds to the last location that has ran.
   FrameStatusMap frame_statuses_;
 
+  // The frame currently being injected into, so long as that frame is valid.
+  content::RenderFrame* valid_running_injection_frame_;
+
   // The collection of RFOHelpers.
   ScopedVector<RFOHelper> rfo_helpers_;
 
   // The set of UserScripts associated with extensions. Owned by the Dispatcher.
   UserScriptSetManager* user_script_set_manager_;
 
   // Pending injections which are waiting for either the proper run location or
   // user consent.
   ScopedVector<ScriptInjection> pending_injections_;
 
   // Running injections which are waiting for async callbacks from blink.
   ScopedVector<ScriptInjection> running_injections_;
 
   ScopedObserver<UserScriptSetManager, UserScriptSetManager::Observer>
       user_script_set_manager_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(ScriptInjectionManager);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_SCRIPT_INJECTION_MANAGER_H_