[SystemInfo API] Finish TODOs in SystemInfoProvider

chrome/browser/extensions/api/system_info_display/display_info_provider.h

 // Copyright (c) 2012 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 CHROME_BROWSER_EXTENSIONS_API_SYSTEM_INFO_DISPLAY_DISPLAY_INFO_PROVIDER_H_
 #define CHROME_BROWSER_EXTENSIONS_API_SYSTEM_INFO_DISPLAY_DISPLAY_INFO_PROVIDER_H_
 
 #include <string>
 
 #include "chrome/browser/extensions/api/system_info/system_info_provider.h"
 #include "chrome/common/extensions/api/system_info_display.h"
 
 namespace extensions {
 
 typedef std::vector<linked_ptr<
     api::system_info_display::DisplayUnitInfo> > DisplayInfo;
 
 class DisplayInfoProvider : public SystemInfoProvider<DisplayInfo> {
  public:
-  typedef base::Callback<void(const DisplayInfo& info, bool success)>
+  typedef base::Callback<void(bool success)>
       RequestInfoCallback;
   typedef base::Callback<void(bool success, const std::string& error)>
       SetInfoCallback;
 
   // Gets a DisplayInfoProvider instance.
   static DisplayInfoProvider* GetProvider();
 
   // Starts request for the display info, redirecting the request to a worker
   // thread if needed (using SystemInfoProvider<DisplayInfo>::StartQuery()).
   // The callback will be called asynchronously.
   // The implementation is platform specific.
   void RequestInfo(const RequestInfoCallback& callback);
 
   // Updates the display parameters for a display with the provided id.
   // The parameters are updated according to content of |info|. After the
   // display is updated, callback is called with the success status, and error
   // message. If the method succeeds, the error message is empty.
   // The callback will be called asynchronously.
   // This functionality is exposed only on ChromeOS.
   virtual void SetInfo(
       const std::string& display_id,
       const api::system_info_display::DisplayProperties& info,
       const SetInfoCallback& callback);
 
+  const DisplayInfo& display_info() const;
+
  protected:
   // Overriden from SystemInfoProvider<DisplayInfo>.
   // The implementation is platform specific.
-  virtual bool QueryInfo(DisplayInfo* info) OVERRIDE;
+  virtual bool QueryInfo() OVERRIDE;
 
   friend class SystemInfoProvider<DisplayInfo>;
 
   DisplayInfoProvider() {}
   virtual ~DisplayInfoProvider() {}
 
   DISALLOW_COPY_AND_ASSIGN(DisplayInfoProvider);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_SYSTEM_INFO_DISPLAY_DISPLAY_INFO_PROVIDER_H_