Use the location where FileDescriptorWatcher is created to track the libevent handlers

base/message_loop/message_pump_io_ios.h

 // Copyright 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_MESSAGE_LOOP_MESSAGE_PUMP_IO_IOS_H_
 #define BASE_MESSAGE_LOOP_MESSAGE_PUMP_IO_IOS_H_
 
 #include "base/base_export.h"
+#include "base/location.h"
 #include "base/mac/scoped_cffiledescriptorref.h"
 #include "base/mac/scoped_cftyperef.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_pump_mac.h"
 #include "base/threading/thread_checker.h"
 
 namespace base {
 
@@ skipping 10 matching lines @@
     virtual void OnFileCanReadWithoutBlocking(int fd) = 0;
     virtual void OnFileCanWriteWithoutBlocking(int fd) = 0;
 
    protected:
     virtual ~Watcher() {}
   };
 
   // Object returned by WatchFileDescriptor to manage further watching.
   class FileDescriptorWatcher {
    public:
-    FileDescriptorWatcher();
+    explicit FileDescriptorWatcher(const tracked_objects::Location& from_here);
     ~FileDescriptorWatcher();  // Implicitly calls StopWatchingFileDescriptor.
 
     // NOTE: These methods aren't called StartWatching()/StopWatching() to
     // avoid confusion with the win32 ObjectWatcher class.
 
     // Stop watching the FD, always safe to call.  No-op if there's nothing
     // to do.
     bool StopWatchingFileDescriptor();
 
+    const tracked_objects::Location& created_from_location() {
+      return created_from_location_;
+    }
+
    private:
     friend class MessagePumpIOSForIO;
     friend class MessagePumpIOSForIOTest;
 
     // Called by MessagePumpIOSForIO, ownership of |fdref| and |fd_source|
     // is transferred to this object.
     void Init(CFFileDescriptorRef fdref,
               CFOptionFlags callback_types,
               CFRunLoopSourceRef fd_source,
               bool is_persistent);
 
     void set_pump(base::WeakPtr<MessagePumpIOSForIO> pump) { pump_ = pump; }
     const base::WeakPtr<MessagePumpIOSForIO>& pump() const { return pump_; }
 
     void set_watcher(Watcher* watcher) { watcher_ = watcher; }
 
     void OnFileCanReadWithoutBlocking(int fd, MessagePumpIOSForIO* pump);
     void OnFileCanWriteWithoutBlocking(int fd, MessagePumpIOSForIO* pump);
 
     bool is_persistent_;  // false if this event is one-shot.
     base::mac::ScopedCFFileDescriptorRef fdref_;
     CFOptionFlags callback_types_;
     base::ScopedCFTypeRef<CFRunLoopSourceRef> fd_source_;
     base::WeakPtr<MessagePumpIOSForIO> pump_;
     Watcher* watcher_;
 
+    tracked_objects::Location created_from_location_;
+
     DISALLOW_COPY_AND_ASSIGN(FileDescriptorWatcher);
   };
 
   enum Mode {
     WATCH_READ = 1 << 0,
     WATCH_WRITE = 1 << 1,
     WATCH_READ_WRITE = WATCH_READ | WATCH_WRITE
   };
 
   MessagePumpIOSForIO();
@@ skipping 28 matching lines @@
   ThreadChecker watch_file_descriptor_caller_checker_;
 
   base::WeakPtrFactory<MessagePumpIOSForIO> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MessagePumpIOSForIO);
 };
 
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_MESSAGE_PUMP_IO_IOS_H_