chrome/browser/net/client_hints.h

   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_