Fix uninitialized field in ScriptInjectionManager

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 <stdint.h>
 
 #include <map>
@@ skipping 102 matching lines @@
   UserScriptSetManager* user_script_set_manager_;
 
   // Pending injections which are waiting for either the proper run location or
   // user consent.
   ScriptInjectionVector pending_injections_;
 
   // Running injections which are waiting for async callbacks from blink.
   ScriptInjectionVector running_injections_;
 
   // Whether or not dom activity should be logged for scripts injected.
-  bool activity_logging_enabled_;
+  bool activity_logging_enabled_ = false;
 
   ScopedObserver<UserScriptSetManager, UserScriptSetManager::Observer>
       user_script_set_manager_observer_;
 
   DISALLOW_COPY_AND_ASSIGN(ScriptInjectionManager);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_SCRIPT_INJECTION_MANAGER_H_