Update stale ThrottlingURLLoader comment

R=kinuko@chromium.org

Change-Id: Ieb2b39c2156521d93ed3cd4a1eb0d8ebb46f2536
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1931161Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Dominic Farolino <dom@chromium.org>
Cr-Commit-Position: refs/heads/master@{#718530}

third_party/blink/public/common/loader/throttling_url_loader.h

@@ -215,7 +215,7 @@ class BLINK_COMMON_EXPORT ThrottlingURLLoader
     uint32_t options;
 
     network::ResourceRequest url_request;
-    // |task_runner_| is used to set up |client_binding_|.
+    // |task_runner| is used to set up |client_receiver_|.
     scoped_refptr<base::SingleThreadTaskRunner> task_runner;
   };
   // Holds any info needed to start or restart the request. Used when start is