Added Client-Hints.

chrome/browser/net/client_hints.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_NET_CLIENT_HINTS_H_
+#define CHROME_BROWSER_NET_CLIENT_HINTS_H_
+
+#include <string>
+
+#include "base/memory/ref_counted.h"
+
+
+// ClientHints is a repository in Chrome for information used
+// to create the Client-Hints request header. For more information, see:
+// https://github.com/igrigorik/http-client-hints/blob/master/
+// draft-grigorik-http-client-hints-00.txt
+

[Ryan Sleevi, 2013/02/08 22:12:53]

nit: delete blank line

[bengr, 2013/02/26 01:57:20]

Done.

+class ClientHints : public base::RefCountedThreadSafe<ClientHints> {

[Ryan Sleevi, 2013/02/08 22:12:53]

Why is this RefCounted? If it's for the UI<->IO thread switch, can you please
re-design it to use WeakPtr, since refcounting is a 'big hammer' to use for
something that is really an internal implementation detail?

[bengr, 2013/02/26 01:57:20]

Done.

+ public:
+  ClientHints();
+
+  // Retrieves screen information for use on the IO thread.
+  bool RetrieveScreenInfo();
+
+  // Returns client hints pertaining to screen information. The format is:
+  // "sh=xx, sw=yy, dpr=zz", where xx, yy, and zz are the screen height,
+  // screen width, and device pixel ratio, respectively. These values are the
+  // same as the values returned by the javascript commands:
+  // screen.height, screen.width, and window.devicePixelRatio.
+  std::string GetScreenInfoHints();
+
+ private:
+  friend class ClientHintsTest;
+  friend class base::RefCountedThreadSafe<ClientHints>;
+
+  ~ClientHints();
+  void FetchScreenInfoOnUIThread();
+  void UpdateScreenInfo(int screen_width, int screen_height,
+                        float device_pixel_ratio);
+
+  std::string screen_hints_;
+
+  DISALLOW_COPY_AND_ASSIGN(ClientHints);
+};
+
+#endif  // CHROME_BROWSER_NET_CLIENT_HINTS_H_