Add calls to the server to request WebAPK updates.

chrome/chrome_browser.gypi

Index: chrome/chrome_browser.gypi
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index f04b6b39160505ce7fbebdea66c396d1fc42f704..fa200130d067b91557245ab345ce21e0d2ec9c89 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -1008,6 +1008,8 @@
       'browser/android/web_contents_factory.h',
       'browser/android/webapk/manifest_upgrade_detector_fetcher.cc',
       'browser/android/webapk/manifest_upgrade_detector_fetcher.h',
+      'browser/android/webapk/webapk_update_manager.cc',
+      'browser/android/webapk/webapk_update_manager.h',
       'browser/android/webapps/add_to_homescreen_data_fetcher.cc',
       'browser/android/webapps/add_to_homescreen_data_fetcher.h',
       'browser/android/webapps/add_to_homescreen_dialog_helper.cc',
@@ -2144,6 +2146,7 @@
       'android/java/src/org/chromium/chrome/browser/webapps/AddToHomescreenDialogHelper.java',
       'android/java/src/org/chromium/chrome/browser/webapps/ManifestUpgradeDetectorFetcher.java',
       'android/java/src/org/chromium/chrome/browser/webapps/WebappRegistry.java',
+      'android/java/src/org/chromium/chrome/browser/webapps/WebApkUpdateManager.java',
     ],
     'chrome_browser_mdns_sources': [
       'browser/local_discovery/service_discovery_client_impl.cc',