Revert of Add WorkerThread based methods for start/stop of worker threads.

content/child/blink_platform_impl.cc

Index: content/child/blink_platform_impl.cc
diff --git a/content/child/blink_platform_impl.cc b/content/child/blink_platform_impl.cc
index 629b90edfb6b89934d3e7c83420014409c718a5c..f0544a86736951fe7c57badf7392f37adb9a21d4 100644
--- a/content/child/blink_platform_impl.cc
+++ b/content/child/blink_platform_impl.cc
@@ -922,16 +922,6 @@
   worker_task_runner->OnWorkerRunLoopStopped(runLoop);
 }
 
-void BlinkPlatformImpl::didStartWorkerThread(blink::WebThread* thread) {
-  WorkerTaskRunner* worker_task_runner = WorkerTaskRunner::Instance();
-  worker_task_runner->OnWorkerThreadStarted(thread);
-}
-
-void BlinkPlatformImpl::didStopWorkerThread(blink::WebThread* thread) {
-  WorkerTaskRunner* worker_task_runner = WorkerTaskRunner::Instance();
-  worker_task_runner->OnWorkerThreadStopped(thread);
-}
-
 blink::WebCrypto* BlinkPlatformImpl::crypto() {
   WebCryptoImpl::EnsureInit();
   return &web_crypto_;