Handle the case when the updates are disabled for a component.

components/update_client/update_checker.cc

Index: components/update_client/update_checker.cc
diff --git a/components/update_client/update_checker.cc b/components/update_client/update_checker.cc
index 95a6a2646f0b81b83f5d7458602630103248614b..459be9f70722e20e6c3e51e735d84e17aa973ef2 100644
--- a/components/update_client/update_checker.cc
+++ b/components/update_client/update_checker.cc
@@ -86,13 +86,19 @@ std::string BuildUpdateCheckRequest(const Configurator& config,
       base::StringAppendF(&app, " brand=\"%s\"", brand.c_str());
     if (item->on_demand)
       base::StringAppendF(&app, " installsource=\"ondemand\"");
-
-    for (const auto& attr : installer_attributes)
+    for (const auto& attr : installer_attributes) {
       base::StringAppendF(&app, " %s=\"%s\"", attr.first.c_str(),
                           attr.second.c_str());
-
+    }
     base::StringAppendF(&app, ">");
-    base::StringAppendF(&app, "<updatecheck />");
+
+    base::StringAppendF(&app, "<updatecheck");
+    if (item->component.supports_group_policy_enable_component_updates &&
+        !config.EnabledComponentUpdates()) {
+      base::StringAppendF(&app, " \"updatedisabled\"=true");

[waffles, 2016/08/03 23:49:02]

I think you mean " updatedisabled=\"true\"". (Also in the tests.)

+    }
+    base::StringAppendF(&app, "/>");
+
     base::StringAppendF(&app, "<ping rd=\"%d\" ping_freshness=\"%s\" />",
                         metadata->GetDateLastRollCall(item->id),
                         metadata->GetPingFreshness(item->id).c_str());