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 c66e5152256f6a459361aa82a614900d8c6dd0f6..1506ee9e33b50bbdecf12764663c869fa3b87808 100644
--- a/chrome/browser/net/chrome_network_delegate.cc
+++ b/chrome/browser/net/chrome_network_delegate.cc
@@ -24,6 +24,7 @@
 #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[] = "Client-Hints";
 
 // If the |request| failed due to problems with a proxy, forward the error to
 // the proxy extension API.
@@ -267,7 +269,7 @@ void RecordContentLengthHistograms(
 
 ChromeNetworkDelegate::ChromeNetworkDelegate(
     extensions::EventRouterForwarder* event_router,
-    BooleanPrefMember* enable_referrers)
+    BooleanPrefMember* enable_referrers, bool enable_client_hints)
     : event_router_(event_router),
       profile_(NULL),
       enable_referrers_(enable_referrers),
@@ -276,9 +278,13 @@ ChromeNetworkDelegate::ChromeNetworkDelegate(
       url_blacklist_manager_(NULL),
       load_time_stats_(NULL),
       received_content_length_(0),
-      original_content_length_(0) {
+      original_content_length_(0),
+      client_hints_(enable_client_hints ? new ClientHints() : NULL){
   DCHECK(event_router);
   DCHECK(enable_referrers);
+  if (client_hints_ != NULL) {

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

Just use a bool check, rather than NULL

if (client_hints_) { }

This works regardless of the storage used for the client hints (eg:
scoped_ptr.get() semantics, implicit pointers, etc)

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

Done.

+    client_hints_->RetrieveScreenInfo();
+  }
 }
 
 ChromeNetworkDelegate::~ChromeNetworkDelegate() {}
@@ -383,6 +389,14 @@ 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();

[igrigorik, 2013/02/09 17:06:30]

Hmm, this would fetch screen.{width,height} on every request, correct? If so,
orientation changes would switch the w/h values in the header. Is there a
simpler approach to just report them as fixed portrait mode? The idea being.. we
don't want to communicate orientation, just the device width and height, which
is fixed.

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

It does not fetch screen height/width on every request. It gets the hints string
on every request. The updating of that string is triggered by
ClientHints::RetrieveScreenInfo(), which only happens once when client hints is
first enabled.

On 2013/02/09 17:06:30, igrigorik wrote:

+    request->SetExtraRequestHeaderByName(kClientHintsHeader,
+                                         client_hints_value, true);
+    DVLOG(2) << kClientHintsHeader << ": " << client_hints_value
+        << " for " << request->url().spec();

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

Align your streams - see http://dev.chromium.org/developers/coding-style

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

Done.

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