Dart: Removes C++ set for closing handles on an unhandled exception.

mojo/public/dart/mojo/sdk_ext/src/natives.dart

 // Copyright 2015 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.
 
 part of internal;
 
 class MojoCoreNatives {
   static int getTimeTicksNow() native "Mojo_GetTimeTicksNow";
 }
 
 class MojoHandleNatives {
-  static int register(Object eventStream, int handle)
-      native "MojoHandle_Register";
+  static Set<int> _unclosedHandles = new Set<int>();
+
+  static void addUnclosed(int handle) {
+    _unclosedHandles.add(handle);
+  }
+
+  static void removeUnclosed(int handle) {
+    _unclosedHandles.remove(handle);
+  }
+
+  static int registerFinalizer(Object eventStream, int handle)
+      native "MojoHandle_RegisterFinalizer";
+
   static int close(int handle) native "MojoHandle_Close";
+
   static List wait(int handle, int signals, int deadline)
       native "MojoHandle_Wait";
+
   static List waitMany(List<int> handles, List<int> signals, int deadline)
       native "MojoHandle_WaitMany";
+
+  // Called from the embedder's unhandled exception callback.
+  // Returns the number of successfully closed handles.
+  static int _closeUnclosedHandles() {
+    int count = 0;
+    _unclosedHandles.forEach((h) {
+      if (MojoHandleNatives.close(h) == 0) {
+        count++;
+      }
+    });
+    _unclosedHandles.clear();
+    return count;
+  }
 }
 
 class MojoHandleWatcherNatives {
   static int sendControlData(
       int controlHandle, int mojoHandle, SendPort port, int data)
       native "MojoHandleWatcher_SendControlData";
   static List recvControlData(int controlHandle)
       native "MojoHandleWatcher_RecvControlData";
   static int setControlHandle(int controlHandle)
       native "MojoHandleWatcher_SetControlHandle";
@@ skipping 44 matching lines @@
 
   static List Duplicate(int bufferHandle, int flags)
       native "MojoSharedBuffer_Duplicate";
 
   static List Map(
       Object buffer, int bufferHandle, int offset, int numBytes, int flags)
       native "MojoSharedBuffer_Map";
 
   static int Unmap(ByteData buffer) native "MojoSharedBuffer_Unmap";
 }