Modify ThreadChecker and NonThreadSafe so that their functionality is

net/url_request/url_request_throttler_manager.cc

Index: net/url_request/url_request_throttler_manager.cc
diff --git a/net/url_request/url_request_throttler_manager.cc b/net/url_request/url_request_throttler_manager.cc
index 39e1f4eb19d1147659be6e2ce0cf6033a52ceeeb..794d59f5b7d6de808fef31504e9bc89fff487def 100644
--- a/net/url_request/url_request_throttler_manager.cc
+++ b/net/url_request/url_request_throttler_manager.cc
@@ -11,31 +11,6 @@
 
 namespace net {
 
-ThreadCheckerForRelease::ThreadCheckerForRelease()
-    : valid_thread_id_(base::kInvalidThreadId) {
-  EnsureThreadIdAssigned();
-}
-
-ThreadCheckerForRelease::~ThreadCheckerForRelease() {}
-
-bool ThreadCheckerForRelease::CalledOnValidThread() const {
-  EnsureThreadIdAssigned();
-  base::AutoLock auto_lock(lock_);
-  return valid_thread_id_ == base::PlatformThread::CurrentId();
-}
-
-void ThreadCheckerForRelease::DetachFromThread() {
-  base::AutoLock auto_lock(lock_);
-  valid_thread_id_ = base::kInvalidThreadId;
-}
-
-void ThreadCheckerForRelease::EnsureThreadIdAssigned() const {
-  base::AutoLock auto_lock(lock_);
-  if (valid_thread_id_ != base::kInvalidThreadId)
-    return;
-  valid_thread_id_ = base::PlatformThread::CurrentId();
-}
-
 const unsigned int URLRequestThrottlerManager::kMaximumNumberOfEntries = 1500;
 const unsigned int URLRequestThrottlerManager::kRequestsBetweenCollecting = 200;