Inject the prodid for the extensions and component updaters.

components/update_client/configurator.h

Index: components/update_client/configurator.h
diff --git a/components/update_client/configurator.h b/components/update_client/configurator.h
index e547d955a8210e922a0066acf39489bf736b893f..14c4b70ca30566534bd1d114a2d6cc1fbbce5eff 100644
--- a/components/update_client/configurator.h
+++ b/components/update_client/configurator.h
@@ -58,6 +58,11 @@ class Configurator : public base::RefCountedThreadSafe<Configurator> {
   // disabled. Similarly, these URLs have a fall back behavior too.
   virtual std::vector<GURL> PingUrl() const = 0;
 
+  // The ProdId is used as a prefix in some of the version strings which appear
+  // in the protocol requests. Possible values include "chrome", "chromecrx",
+  // "chromium", "chromiumcrx", and "unknown".

[waffles, 2016/09/15 18:14:11]

(FWIW, "chromium" is not a possible value.)

+  virtual std::string GetProdId() const = 0;
+
   // Version of the application. Used to compare the component manifests.
   virtual base::Version GetBrowserVersion() const = 0;