Never lock the Pepper proxy lock on the IO thread

ppapi/shared_impl/callback_tracker.cc

 // Copyright (c) 2010 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.
 
 #include "ppapi/shared_impl/callback_tracker.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 34 matching lines @@
   {
     base::AutoLock acquire(lock_);
     CallbackSetMap::iterator iter = pending_callbacks_.find(resource_id);
     // The resource may have no callbacks, so it won't be found, and we're done.
     if (iter == pending_callbacks_.end())
       return;
     // Copy the set so we can drop the lock before calling in to
     // TrackedCallback.
     callbacks_for_resource = iter->second;
   }
-  for (const auto& iter : callbacks_for_resource) {
+  for (const auto& iter : callbacks_for_resource)
     iter->PostAbort();
-  }
 }
 
 CallbackTracker::~CallbackTracker() {
   // All callbacks must be aborted before destruction.
   CHECK_EQ(0u, pending_callbacks_.size());
 }
 
 void CallbackTracker::Add(
     const scoped_refptr<TrackedCallback>& tracked_callback) {
   base::AutoLock acquire(lock_);
@@ skipping 12 matching lines @@
   CallbackSet::iterator it = map_it->second.find(tracked_callback);
   DCHECK(it != map_it->second.end());
   map_it->second.erase(it);
 
   // If there are no pending callbacks left for this ID, get rid of the entry.
   if (map_it->second.empty())
     pending_callbacks_.erase(map_it);
 }
 
 }  // namespace ppapi