Prevent duplicate content script injection defined in manifest.json

extensions/renderer/scripts_run_info.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_SCRIPTS_RUN_INFO_H_
 #define EXTENSIONS_RENDERER_SCRIPTS_RUN_INFO_H_
 
 #include <stddef.h>
 
 #include <map>
@@ skipping 22 matching lines @@
   // The number of CSS scripts injected.
   size_t num_css;
   // The number of JS scripts injected.
   size_t num_js;
   // The number of blocked JS scripts injected.
   size_t num_blocking_js;
   // A map of extension ids to executing script paths.
   ExecutingScriptsMap executing_scripts;
   // The elapsed time since the ScriptsRunInfo was constructed.
   base::ElapsedTimer timer;
+  // A list of pathnames of executing scripts

[Devlin, 2016/07/12 23:32:36]

nit: comment needs a period.  Also, I'd probably replace pathnames with
"extension urls".

[catmullings, 2016/07/13 17:25:34]

Done.

+  std::set<GURL> injected_scripts;
 
   // Log information about a given script run. If |send_script_activity| is
   // true, this also informs the browser of the script run.
   void LogRun(bool send_script_activity);
 
  private:
   // The routinig id to use to notify the browser of any injections. Since the
   // frame may be deleted in injection, we don't hold on to a reference to it
   // directly.
   int routing_id_;
 
   // The run location at which injection is happening.
   UserScript::RunLocation run_location_;
 
   // The url of the frame, preserved for the same reason as the routing id.
   GURL frame_url_;
 
   DISALLOW_COPY_AND_ASSIGN(ScriptsRunInfo);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_SCRIPTS_RUN_INFO_H_