webstorePrivate: Support an |authuser| property in beginInstallWithManifest3.

chrome/browser/extensions/api/webstore_private/webstore_private_api.h

 // Copyright (c) 2012 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 CHROME_BROWSER_EXTENSIONS_API_WEBSTORE_PRIVATE_WEBSTORE_PRIVATE_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_WEBSTORE_PRIVATE_WEBSTORE_PRIVATE_API_H_
 
 #include <string>
 
 #include "chrome/browser/extensions/bundle_installer.h"
@@ skipping 151 matching lines @@
   SkBitmap icon_;
 
   // A dummy Extension object we create for the purposes of using
   // ExtensionInstallPrompt to prompt for confirmation of the install.
   scoped_refptr<extensions::Extension> dummy_extension_;
 
   // The class that displays the install prompt.
   scoped_ptr<ExtensionInstallPrompt> install_prompt_;
 
   scoped_ptr<SigninTracker> signin_tracker_;
+
+  // The authuser query parameter value which should be used with CRX download
+  // requests. This is empty if authuser should not be set on download requests.
+  std::string authuser_;
 };
 
 class WebstorePrivateCompleteInstallFunction
     : public ChromeAsyncExtensionFunction,
       public WebstoreInstaller::Delegate {
  public:
   DECLARE_EXTENSION_FUNCTION("webstorePrivate.completeInstall",
                              WEBSTOREPRIVATE_COMPLETEINSTALL)
 
   WebstorePrivateCompleteInstallFunction();
@@ skipping 153 matching lines @@
   SigninManagerBase* signin_manager_;
 
   // Tracks changes to sign-in state. Used to notify the page when an existing
   // in-progress sign-in completes, either with success or failure.
   scoped_ptr<SigninTracker> signin_tracker_;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_WEBSTORE_PRIVATE_WEBSTORE_PRIVATE_API_H_