Make FileReader return ownership of the string content

extensions/browser/api/execute_code_function.h

 // Copyright (c) 2013 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_BROWSER_API_EXECUTE_CODE_FUNCTION_H_
 #define EXTENSIONS_BROWSER_API_EXECUTE_CODE_FUNCTION_H_
 
 #include "base/macros.h"
 #include "extensions/browser/extension_function.h"
 #include "extensions/browser/script_executor.h"
@@ skipping 25 matching lines @@
   virtual const GURL& GetWebViewSrc() const = 0;
   virtual void OnExecuteCodeFinished(const std::string& error,
                                      const GURL& on_url,
                                      const base::ListValue& result);
 
   virtual bool LoadFile(const std::string& file);
 
   // Called when contents from the loaded file have been localized.
   void DidLoadAndLocalizeFile(const std::string& file,
                               bool success,
-                              const std::string& data);
+                              std::unique_ptr<std::string> data);
 
   const HostID& host_id() const { return host_id_; }
   void set_host_id(const HostID& host_id) { host_id_ = host_id; }
 
   // The injection details.
   std::unique_ptr<api::extension_types::InjectDetails> details_;
 
  private:
   // Called when contents from the file whose path is specified in JSON
   // arguments has been loaded.
-  void DidLoadFile(bool success, const std::string& data);
+  void DidLoadFile(bool success, std::unique_ptr<std::string> data);
 
   // Runs on FILE thread. Loads message bundles for the extension and
   // localizes the CSS data. Calls back DidLoadAndLocalizeFile on the UI thread.
   void GetFileURLAndLocalizeCSS(ScriptExecutor::ScriptType script_type,
-                                const std::string& data,
+                                std::unique_ptr<std::string> data,
                                 const std::string& extension_id,
                                 const base::FilePath& extension_path,
                                 const std::string& extension_default_locale);
 
   // Run in UI thread.  Code string contains the code to be executed. Returns
   // true on success. If true is returned, this does an AddRef.
   bool Execute(const std::string& code_string);
 
   // Contains extension resource built from path of file which is
   // specified in JSON arguments.
   ExtensionResource resource_;
 
   // The URL of the file being injected into the page.
   GURL file_url_;
 
   // The ID of the injection host.
   HostID host_id_;
 
   DISALLOW_COPY_AND_ASSIGN(ExecuteCodeFunction);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_EXECUTE_CODE_FUNCTION_H_