1 // Copyright 2013 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef CHROME_BROWSER_NET_CLIENT_HINTS_H_ 6 #define CHROME_BROWSER_NET_CLIENT_HINTS_H_ 7 8 #include <string> 9 10 #include "base/basictypes.h" 11 #include "base/memory/weak_ptr.h" 12 13 // ClientHints is a repository in Chrome for information used 14 // to create the Client-Hints request header. For more information, see: 15 // https://github.com/igrigorik/http-client-hints/blob/draft2/draft-grigorik-http-client-hints-01.txt 16 class ClientHints { 17 public: 18 static const char kDevicePixelRatioHeader[]; 19 20 ClientHints(); 21 ~ClientHints(); 22 23 void Init(); 24 25 // Returns the device pixel ratio as a string. Its value is the same as 26 // window.devicePixelRatio in Javascript. 27 const std::string& GetDevicePixelRatioHeader() const; 28 29 private: 30 friend class ClientHintsTest; 31 32 // Retrieves and updates screen information for use on the IO thread. 33 bool RetrieveScreenInfo(); 34 35 void UpdateScreenInfo(float device_pixel_ratio_value); 36 37 std::string screen_hints_; 38 39 base::WeakPtrFactory<ClientHints> weak_ptr_factory_; 40 41 DISALLOW_COPY_AND_ASSIGN(ClientHints); 42 }; 43 44 #endif // CHROME_BROWSER_NET_CLIENT_HINTS_H_ 45
