Update from chromium a8e7c94b1b79a0948d05a1fcfff53391d22ce37a

base/memory/weak_ptr.h

 // Copyright (c) 2012 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.
 
 // Weak pointers are pointers to an object that do not affect its lifetime,
 // and which may be invalidated (i.e. reset to NULL) by the object, or its
 // owner, at any time, most commonly when the object is about to be deleted.
 
 // Weak pointers are useful when an object needs to be accessed safely by one
 // or more objects other than its owner, and those callers can cope with the
@@ skipping 30 matching lines @@
 //    WeakPtr<Controller> controller_;
 //  };
 //
 // With this implementation a caller may use SpawnWorker() to dispatch multiple
 // Workers and subsequently delete the Controller, without waiting for all
 // Workers to have completed.
 
 // ------------------------- IMPORTANT: Thread-safety -------------------------
 
 // Weak pointers may be passed safely between threads, but must always be
-// dereferenced and invalidated on the same thread otherwise checking the
-// pointer would be racey.
+// dereferenced and invalidated on the same SequencedTaskRunner otherwise
+// checking the pointer would be racey.
 //
 // To ensure correct use, the first time a WeakPtr issued by a WeakPtrFactory
 // is dereferenced, the factory and its WeakPtrs become bound to the calling
-// thread, and cannot be dereferenced or invalidated on any other thread. Bound
-// WeakPtrs can still be handed off to other threads, e.g. to use to post tasks
-// back to object on the bound thread.
+// thread or current SequencedWorkerPool token, and cannot be dereferenced or
+// invalidated on any other task runner. Bound WeakPtrs can still be handed
+// off to other task runners, e.g. to use to post tasks back to object on the
+// bound sequence.
 //
-// Invalidating the factory's WeakPtrs un-binds it from the thread, allowing it
-// to be passed for a different thread to use or delete it.
+// Invalidating the factory's WeakPtrs un-binds it from the sequence, allowing
+// it to be passed for a different sequence to use or delete it.
 
 #ifndef BASE_MEMORY_WEAK_PTR_H_
 #define BASE_MEMORY_WEAK_PTR_H_
 
 #include "base/basictypes.h"
 #include "base/base_export.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
 #include "base/sequence_checker.h"
 #include "base/template_util.h"
 
 namespace base {
 
 template <typename T> class SupportsWeakPtr;
 template <typename T> class WeakPtr;
 
 namespace internal {
 // These classes are part of the WeakPtr implementation.
 // DO NOT USE THESE CLASSES DIRECTLY YOURSELF.
 
 class BASE_EXPORT WeakReference {
  public:
-  // Although Flag is bound to a specific thread, it may be deleted from another
-  // via base::WeakPtr::~WeakPtr().
+  // Although Flag is bound to a specific SequencedTaskRunner, it may be
+  // deleted from another via base::WeakPtr::~WeakPtr().
   class BASE_EXPORT Flag : public RefCountedThreadSafe<Flag> {
    public:
     Flag();
 
     void Invalidate();
     bool IsValid() const;
 
    private:
     friend class base::RefCountedThreadSafe<Flag>;
 
@@ skipping 233 matching lines @@
 //   base::WeakPtr<Derived> ptr = derived.AsWeakPtr();  // Fails.
 
 template <typename Derived>
 WeakPtr<Derived> AsWeakPtr(Derived* t) {
   return internal::SupportsWeakPtrBase::StaticAsWeakPtr<Derived>(t);
 }
 
 }  // namespace base
 
 #endif  // BASE_MEMORY_WEAK_PTR_H_