Pass FROM_HERE to ObserverListThreadSafe::Notify to improve profile.

base/observer_list_threadsafe.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.
 
 #ifndef BASE_OBSERVER_LIST_THREADSAFE_H_
 #define BASE_OBSERVER_LIST_THREADSAFE_H_
 
 #include <algorithm>
 #include <map>
 
@@ skipping 150 matching lines @@
     base::AutoLock lock(list_lock_);
     DCHECK(observer_lists_.empty());
   }
 
   // Notify methods.
   // Make a thread-safe callback to each Observer in the list.
   // Note, these calls are effectively asynchronous.  You cannot assume
   // that at the completion of the Notify call that all Observers have
   // been Notified.  The notification may still be pending delivery.
   template <class Method, class... Params>
-  void Notify(Method m, const Params&... params) {
+  void Notify(const tracked_objects::Location& from_here,
+              Method m,
+              const Params&... params) {
     UnboundMethod<ObserverType, Method, Tuple<Params...>> method(
         m, MakeTuple(params...));
 
     base::AutoLock lock(list_lock_);
     for (const auto& entry : observer_lists_) {
       ObserverListContext* context = entry.second;
       context->loop->PostTask(
-          FROM_HERE,
+          from_here,
           base::Bind(
               &ObserverListThreadSafe<ObserverType>::template NotifyWrapper<
                   Method, Tuple<Params...>>,
               this, context, method));
     }
   }
 
  private:
   // See comment above ObserverListThreadSafeTraits' definition.
   friend struct ObserverListThreadSafeTraits<ObserverType>;
@@ skipping 65 matching lines @@
       ObserversListMap;
 
   mutable base::Lock list_lock_;  // Protects the observer_lists_.
   ObserversListMap observer_lists_;
   const NotificationType type_;
 
   DISALLOW_COPY_AND_ASSIGN(ObserverListThreadSafe);
 };
 
 #endif  // BASE_OBSERVER_LIST_THREADSAFE_H_