Update from https://crrev.com/312398

base/cancelable_callback.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // CancelableCallback is a wrapper around base::Callback that allows
 // cancellation of a callback. CancelableCallback takes a reference on the
 // wrapped callback until this object is destroyed or Reset()/Cancel() are
 // called.
 //
 // NOTE:
@@ skipping 44 matching lines @@
 template <typename Sig>
 class CancelableCallback;
 
 template <typename... A>
 class CancelableCallback<void(A...)> {
  public:
   CancelableCallback() : weak_factory_(this) {}
 
   // |callback| must not be null.
   explicit CancelableCallback(const base::Callback<void(A...)>& callback)
-      : weak_factory_(this),
-        callback_(callback) {
+      : callback_(callback), weak_factory_(this) {
     DCHECK(!callback.is_null());
     InitializeForwarder();
   }
 
   ~CancelableCallback() {}
 
   // Cancels and drops the reference to the wrapped callback.
   void Cancel() {
     weak_factory_.InvalidateWeakPtrs();
     forwarder_.Reset();
@@ skipping 29 matching lines @@
     callback_.Run(args...);
   }
 
   // Helper method to bind |forwarder_| using a weak pointer from
   // |weak_factory_|.
   void InitializeForwarder() {
     forwarder_ = base::Bind(&CancelableCallback<void(A...)>::Forward,
                             weak_factory_.GetWeakPtr());
   }
 
-  // Used to ensure Forward() is not run when this object is destroyed.
-  // TODO(ckehoe): This should be the last class member.
-  // Move it there when crbug.com/433583 is fixed.
-  base::WeakPtrFactory<CancelableCallback<void(A...)> > weak_factory_;
-
   // The wrapper closure.
   base::Callback<void(A...)> forwarder_;
 
   // The stored closure that may be cancelled.
   base::Callback<void(A...)> callback_;
 
+  // Used to ensure Forward() is not run when this object is destroyed.
+  base::WeakPtrFactory<CancelableCallback<void(A...)>> weak_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(CancelableCallback);
 };
 
 typedef CancelableCallback<void(void)> CancelableClosure;
 
 }  // namespace base
 
 #endif  // BASE_CANCELABLE_CALLBACK_H_