Revert of Rate limit programmatic update checks for extensions

extensions/browser/updater/extension_downloader.h

Index: extensions/browser/updater/extension_downloader.h
diff --git a/extensions/browser/updater/extension_downloader.h b/extensions/browser/updater/extension_downloader.h
index 3de9b132bd5621b31343a42bc1478f72a0e1d58d..81b9134ed0fa1a8c50db5013b213cb40540ab819 100644
--- a/extensions/browser/updater/extension_downloader.h
+++ b/extensions/browser/updater/extension_downloader.h
@@ -46,7 +46,6 @@
 };
 
 class ExtensionCache;
-class ExtensionDownloaderTestDelegate;
 class ExtensionUpdaterTest;
 
 // A class that checks for updates of a given list of extensions, and downloads
@@ -114,10 +113,6 @@
   void set_enable_extra_update_metrics(bool enable) {
     enable_extra_update_metrics_ = enable;
   }
-
-  // Sets a test delegate to use by any instances of this class. The |delegate|
-  // should outlive all instances.
-  static void set_test_delegate(ExtensionDownloaderTestDelegate* delegate);
 
   // These are needed for unit testing, to help identify the correct mock
   // URLFetcher objects.