Inject the prodid for the extensions and component updaters.

components/update_client/configurator.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_UPDATE_CLIENT_CONFIGURATOR_H_
 #define COMPONENTS_UPDATE_CLIENT_CONFIGURATOR_H_
 
 #include <memory>
 #include <string>
 #include <vector>
@@ skipping 40 matching lines @@
   virtual int UpdateDelay() const = 0;
 
   // The URLs for the update checks. The URLs are tried in order, the first one
   // that succeeds wins.
   virtual std::vector<GURL> UpdateUrl() const = 0;
 
   // The URLs for pings. Returns an empty vector if and only if pings are
   // 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;
 
   // Returns the value we use for the "updaterchannel=" and "prodchannel="
   // parameters. Possible return values include: "canary", "dev", "beta", and
   // "stable".
   virtual std::string GetChannel() const = 0;
 
   // Returns the brand code or distribution tag that has been assigned to
   // a partner. A brand code is a 4-character string used to identify
@@ skipping 57 matching lines @@
 
  protected:
   friend class base::RefCountedThreadSafe<Configurator>;
 
   virtual ~Configurator() {}
 };
 
 }  // namespace update_client
 
 #endif  // COMPONENTS_UPDATE_CLIENT_CONFIGURATOR_H_