[Extensions] Handle some funny cases in script injection

extensions/renderer/programmatic_script_injector.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_PROGRAMMATIC_SCRIPT_INJECTOR_H_
 #define EXTENSIONS_RENDERER_PROGRAMMATIC_SCRIPT_INJECTOR_H_
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/values.h"
 #include "extensions/renderer/script_injection.h"
 #include "url/gurl.h"
 
 struct ExtensionMsg_ExecuteCode_Params;
 
 namespace content {
 class RenderFrame;
 }
 
 namespace extensions {
 
 // A ScriptInjector to handle tabs.executeScript().
 class ProgrammaticScriptInjector : public ScriptInjector {
  public:
   ProgrammaticScriptInjector(const ExtensionMsg_ExecuteCode_Params& params,
                              content::RenderFrame* render_frame);
   ~ProgrammaticScriptInjector() override;
 
  private:
+  class FrameWatcher;
+
   // ScriptInjector implementation.
   UserScript::InjectionType script_type() const override;
   bool ShouldExecuteInMainWorld() const override;
   bool IsUserGesture() const override;
   bool ExpectsResults() const override;
   bool ShouldInjectJs(UserScript::RunLocation run_location) const override;
   bool ShouldInjectCss(UserScript::RunLocation run_location) const override;
   PermissionsData::AccessType CanExecuteOnFrame(
       const InjectionHost* injection_host,
       blink::WebLocalFrame* web_frame,
@@ skipping 19 matching lines @@
   scoped_ptr<ExtensionMsg_ExecuteCode_Params> params_;
 
   // The url of the frame into which we are injecting.
   GURL url_;
 
   // The URL of the frame's origin. This is usually identical to |url_|, but
   // could be different for e.g. about:blank URLs. Do not use this value to make
   // security decisions, to avoid race conditions (e.g. due to navigation).
   GURL effective_url_;
 
-  // The RenderFrame to which we send the response upon completion.
-  content::RenderFrame* render_frame_;
+  // A helper class to hold the render frame and watch for its deletion.
+  scoped_ptr<FrameWatcher> frame_watcher_;
 
   // The results of the script execution.
   base::ListValue results_;
 
   // Whether or not this script injection has finished.
   bool finished_;
 
   DISALLOW_COPY_AND_ASSIGN(ProgrammaticScriptInjector);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_PROGRAMMATIC_SCRIPT_INJECTOR_H_