Transmit a X-Chrome-UMA-Enabled bit to Google domains from clients that have UMA enabled.

chrome/browser/net/chrome_network_delegate.h

Index: chrome/browser/net/chrome_network_delegate.h
diff --git a/chrome/browser/net/chrome_network_delegate.h b/chrome/browser/net/chrome_network_delegate.h
index a582c388f1dfee223c44229f80cc69d40481944c..e8ef807b1925e2edbc8fa8df74df45cbb5f6dbcb 100644
--- a/chrome/browser/net/chrome_network_delegate.h
+++ b/chrome/browser/net/chrome_network_delegate.h
@@ -39,6 +39,7 @@ class ChromeNetworkDelegate : public net::NetworkDelegate {
       const policy::URLBlacklistManager* url_blacklist_manager,
       void* profile,
       CookieSettings* cookie_settings,
+      bool is_incognito,
       BooleanPrefMember* enable_referrers);
   virtual ~ChromeNetworkDelegate();
 
@@ -83,10 +84,20 @@ class ChromeNetworkDelegate : public net::NetworkDelegate {
                             const std::string& cookie_line,
                             net::CookieOptions* options) OVERRIDE;
 
+  // Adds Chrome experiment and metrics state as custom headers to |headers|
+  // based on local state and |request|.
+  void AddChromeMetricsStateHeader(net::URLRequest* request,
+                                   net::HttpRequestHeaders* headers);
+
   scoped_refptr<ExtensionEventRouterForwarder> event_router_;
   void* profile_;
   scoped_refptr<CookieSettings> cookie_settings_;
 
+  // Whether or not the profile is an Off The Record profile. Note that this
+  // field is not valid if |profile_| is NULL, so always check profile_ first
+  // before this field.
+  bool is_incognito_;
+
   scoped_refptr<ExtensionInfoMap> extension_info_map_;
 
   // Weak, owned by our owner.