Send platform_version to Gaia for Dent auth flow

Reland of https://crrev.com/c/2121264, since getAccounts is already
implemented.

Bug: 1064677, b/123630392
Change-Id: Ic132d1fdfb5ef12a3ef70a6e064319ce904a6965
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2410858Reviewed-by: Kush Sinha <sinhak@chromium.org>
Reviewed-by: Roman Sorokin [CET] <rsorokin@chromium.org>
Commit-Queue: Anastasiia N <anastasiian@chromium.org>
Cr-Commit-Position: refs/heads/master@{#808848}

chrome/browser/resources/gaia_auth_host/authenticator.js

@@ -55,6 +55,7 @@ cr.define('cr.login', function() {
    *   isLoginPrimaryAccount: boolean,
    *   email: string,
    *   constrained: string,
+   *   platformVersion: string,
    *   readOnlyEmail: boolean,
    *   service: string,
    *   dontResizeNonEmbeddedPages: boolean,

chrome/browser/ui/webui/signin/inline_login_handler_chromeos.cc

@@ -26,6 +26,7 @@
 #include "chrome/common/pref_names.h"
 #include "chromeos/components/account_manager/account_manager_factory.h"
 #include "chromeos/constants/chromeos_features.h"
+#include "chromeos/dbus/util/version_loader.h"
 #include "components/prefs/pref_service.h"
 #include "components/signin/public/identity_manager/account_info.h"
 #include "components/signin/public/identity_manager/identity_manager.h"
@@ -281,6 +282,9 @@ void InlineLoginHandlerChromeOS::SetExtraInitParams(
   const GURL& url = gaia_urls->embedded_setup_chromeos_url(2U);
   params.SetKey("gaiaPath", base::Value(url.path().substr(1)));
 
+  params.SetKey(
+      "platformVersion",
+      base::Value(version_loader::GetVersion(version_loader::VERSION_SHORT)));
   params.SetKey("constrained", base::Value("1"));
   params.SetKey("flow", base::Value(GetInlineLoginFlowName(
                             Profile::FromWebUI(web_ui()),