Variations seed is pulled from the Java application on the first launch of Chrome

chrome/browser/metrics/variations/chrome_variations_service_client.cc

 // Copyright 2015 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.
 
 #include "chrome/browser/metrics/variations/chrome_variations_service_client.h"
 
 #include "base/bind.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/common/channel_info.h"
 #include "components/version_info/version_info.h"
@@ skipping 61 matching lines @@
     std::string* parameter) {
 #if defined(OS_CHROMEOS)
   chromeos::CrosSettings::Get()->GetString(
       chromeos::kVariationsRestrictParameter, parameter);
   return true;
 #else
   return false;
 #endif
 }
 
+#if defined(OS_ANDROID)
+base::Callback<void(std::string*, std::string*, std::string*)>
+ChromeVariationsServiceClient::GetVariationsFirstRunSeedCallback() {
+  return base::Bind(&PrefServiceBridge::GetVariationsFirstRunSeed);
+}
+#endif  // OS_ANDROID
+
 void ChromeVariationsServiceClient::OnInitialStartup() {
 #if defined(OS_WIN)
   StartGoogleUpdateRegistrySync();
 #endif
 }
 
 #if defined(OS_WIN)
 void ChromeVariationsServiceClient::StartGoogleUpdateRegistrySync() {
   registry_syncer_.RequestRegistrySync();
 }
 #endif