Send traffic-management headers from extension updater.

chrome/browser/extensions/updater/extension_updater.h

Index: chrome/browser/extensions/updater/extension_updater.h
diff --git a/chrome/browser/extensions/updater/extension_updater.h b/chrome/browser/extensions/updater/extension_updater.h
index 65ddd996e12314241d427a9933f57c68a491c181..132adb262b52e55324e7a42ad9539e2406c81eb9 100644
--- a/chrome/browser/extensions/updater/extension_updater.h
+++ b/chrome/browser/extensions/updater/extension_updater.h
@@ -69,6 +69,11 @@ class ExtensionUpdater : public ExtensionDownloaderDelegate,
     // right away.
     bool install_immediately;
 
+    // An extension update check can be originated by a user or by a timer.
+    // When the value of |on_demand_update| is true, the update request was
+    // initiated by a user.
+    bool on_demand_update;

[waffles, 2017/03/21 21:42:01]

I recommend standardizing on "foreground" or "foreground_check" so that the
meaning of this bool is semantically consistent with the header value.

[Minh X. Nguyen, 2017/03/21 22:17:05]

Done.

+
     // Callback to call when the update check is complete. Can be null, if
     // you're not interested in when this happens.
     FinishedCallback callback;
@@ -167,7 +172,8 @@ class ExtensionUpdater : public ExtensionDownloaderDelegate,
   // ignoring |pending_ids| so the extension isn't fetched again.
   void AddToDownloader(const ExtensionSet* extensions,
                        const std::list<std::string>& pending_ids,
-                       int request_id);
+                       int request_id,
+                       bool on_demand_update);
 
   // BaseTimer::ReceiverMethod callback.
   void TimerFired();