[Extensions] Add renderer-side logic to short circuit activity logging

extensions/renderer/user_script_set_manager.h

Index: extensions/renderer/user_script_set_manager.h
diff --git a/extensions/renderer/user_script_set_manager.h b/extensions/renderer/user_script_set_manager.h
index af7611e19ca53ab811397ad69b1b79b26e0573fe..8d38f726c60f325268e3f8d7e8838fdcb920f6d1 100644
--- a/extensions/renderer/user_script_set_manager.h
+++ b/extensions/renderer/user_script_set_manager.h
@@ -81,6 +81,10 @@ class UserScriptSetManager : public content::RenderThreadObserver {
 
   const UserScriptSet* static_scripts() const { return &static_scripts_; }
 
+  void set_activity_logging_enabled(bool enabled) {
+    activity_logging_enabled_ = enabled;
+  }
+
  private:
   // Map for per-extension sets that may be defined programmatically.
   typedef std::map<HostID, linked_ptr<UserScriptSet> > UserScriptSetMap;
@@ -103,6 +107,9 @@ class UserScriptSetManager : public content::RenderThreadObserver {
   // per-extension).
   UserScriptSetMap programmatic_scripts_;
 
+  // Whether or not dom activity should be logged for injected scripts.
+  bool activity_logging_enabled_;
+
   // The associated observers.
   base::ObserverList<Observer> observers_;