Added Client-Hints.

chrome/browser/net/client_hints.cc

Index: chrome/browser/net/client_hints.cc
diff --git a/chrome/browser/net/client_hints.cc b/chrome/browser/net/client_hints.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c3186dc35f564caee58685e66b29c3901556b8b3
--- /dev/null
+++ b/chrome/browser/net/client_hints.cc
@@ -0,0 +1,50 @@
+// 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.
+
+#include "chrome/browser/net/client_hints.h"
+
+#include "base/bind.h"
+#include "base/stringprintf.h"
+#include "content/public/browser/browser_thread.h"
+#include "ui/gfx/screen.h"
+
+namespace {
+
+void FetchScreenInfoOnUIThread(ClientHints::ScreenInfo* info) {
+  DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::UI));
+  gfx::Display display = gfx::Screen::GetNativeScreen()->GetPrimaryDisplay();
+  info->width = display.GetSizeInPixel().width();
+  info->height = display.GetSizeInPixel().height();
+  info->pixel_ratio = display.device_scale_factor();
+}
+
+}  // namespace
+
+ClientHints::ClientHints() : screen_hints_(""), weak_ptr_factory_(this) {

[Ryan Sleevi, 2013/02/26 18:26:16]

You will need to rewrite this (to suppress an MSVC warning) as

ClientHints::ClientHints :
weak_ptr_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {}

Note that I also removed the screen_hints("") - there is no need to initialize
to an empty string here, let the default ctor handle that.

[bengr, 2013/02/26 18:41:16]

Done.

+}
+
+ClientHints::~ClientHints() {
+}
+
+bool ClientHints::RetrieveScreenInfo() {

[Ryan Sleevi, 2013/02/26 18:26:16]

DCHECK(content::BrowserThread::CurrentlyOn(content::BrowserThread::IO))

Simply because with the PTAR pattern, you are able to call from any thread.

[bengr, 2013/02/26 18:41:16]

Done.

+  ClientHints::ScreenInfo* info = new ClientHints::ScreenInfo();
+  return content::BrowserThread::PostTaskAndReply(
+      content::BrowserThread::UI,
+      FROM_HERE,
+      base::Bind(&FetchScreenInfoOnUIThread, info),
+      base::Bind(&ClientHints::UpdateScreenInfo, weak_ptr_factory_.GetWeakPtr(),
+           base::Owned(info)));

[Ryan Sleevi, 2013/02/26 18:26:16]

nit: indent to (, following function-call indenting.

[bengr, 2013/02/26 18:41:16]

Done.

+}
+
+std::string ClientHints::GetScreenInfoHints() {
+  return screen_hints_;
+}
+
+void ClientHints::UpdateScreenInfo(ClientHints::ScreenInfo* info) {
+  if (info->height > 0 && info->width > 0 && info->pixel_ratio > 0.0)

[Ryan Sleevi, 2013/02/26 18:26:16]

nit: braces here, for a multi-line body (even if it's wrapped)

[bengr, 2013/02/26 18:41:16]

Done.

+    screen_hints_ = base::StringPrintf(
+        "dh=%d, dw=%d, dpr=%0.3g",
+        info->height, info->width, info->pixel_ratio);
+}
+