Added Client-Hints.

chrome/browser/net/chrome_network_delegate.cc

Index: chrome/browser/net/chrome_network_delegate.cc
diff --git a/chrome/browser/net/chrome_network_delegate.cc b/chrome/browser/net/chrome_network_delegate.cc
index 93ff16ac99b600b476b5a47f4f65466e55e8f030..db3b20d3ed575f3a67cf76860eb101bbb24bff4c 100644
--- a/chrome/browser/net/chrome_network_delegate.cc
+++ b/chrome/browser/net/chrome_network_delegate.cc
@@ -25,6 +25,7 @@
 #include "chrome/browser/extensions/extension_process_manager.h"
 #include "chrome/browser/extensions/extension_system.h"
 #include "chrome/browser/google/google_util.h"
+#include "chrome/browser/net/client_hints.h"
 #include "chrome/browser/net/connect_interceptor.h"
 #include "chrome/browser/net/load_time_stats.h"
 #include "chrome/browser/performance_monitor/performance_monitor.h"
@@ -75,6 +76,7 @@ bool ChromeNetworkDelegate::g_never_throttle_requests_ = false;
 namespace {
 
 const char kDNTHeader[] = "DNT";
+const char kClientHintsHeader[] = "CH";
 
 // If the |request| failed due to problems with a proxy, forward the error to
 // the proxy extension API.
@@ -299,6 +301,11 @@ void ChromeNetworkDelegate::set_predictor(
       new chrome_browser_net::ConnectInterceptor(predictor));
 }
 
+void ChromeNetworkDelegate::set_enable_client_hints() {
+  client_hints_= new ClientHints();
+  client_hints_->RetrieveScreenInfo();
+}
+
 // static
 void ChromeNetworkDelegate::NeverThrottleRequests() {
   g_never_throttle_requests_ = true;
@@ -383,6 +390,14 @@ int ChromeNetworkDelegate::OnBeforeURLRequest(
   if (enable_do_not_track_ && enable_do_not_track_->GetValue())
     request->SetExtraRequestHeaderByName(kDNTHeader, "1", true /* override */);
 
+  if (client_hints_ != NULL) {
+    std::string client_hints_value = client_hints_->GetScreenInfoHints();
+    request->SetExtraRequestHeaderByName(kClientHintsHeader,
+                                         client_hints_value, true);
+    DVLOG(2) << kClientHintsHeader << ": " << client_hints_value
+             << " for " << request->url().spec();

[Ryan Sleevi, 2013/02/26 02:21:04]

nit: Is it necessary to DVLOG this? Seems like you'll be able to snarf it in
net-internals.

[bengr, 2013/02/26 18:19:53]

Done.

+  }
+
   bool force_safe_search = force_google_safe_search_ &&
                            force_google_safe_search_->GetValue();