Simplify invokeCallback() and support void return values for IDL callbacks

Source/modules/filesystem/DOMFileSystemSync.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 166 matching lines @@
 
 namespace {
 
 class ReceiveFileWriterCallback : public FileWriterBaseCallback {
 public:
     static PassOwnPtr<ReceiveFileWriterCallback> create()
     {
         return adoptPtr(new ReceiveFileWriterCallback());
     }
 
-    bool handleEvent(FileWriterBase*)
+    void handleEvent(FileWriterBase*)
     {
-        return true;
     }
 
 private:
     ReceiveFileWriterCallback()
     {
     }
 };
 
 class LocalErrorCallback : public ErrorCallback {
 public:
     static PassOwnPtr<LocalErrorCallback> create(FileError::ErrorCode& errorCode)
     {
         return adoptPtr(new LocalErrorCallback(errorCode));
     }
 
-    bool handleEvent(FileError* error)
+    void handleEvent(FileError* error)
     {
         ASSERT(error->code() != FileError::OK);
         m_errorCode = error->code();
-        return true;
     }
 
 private:
     explicit LocalErrorCallback(FileError::ErrorCode& errorCode)
         : m_errorCode(errorCode)
     {
     }
 
     FileError::ErrorCode& m_errorCode;
 };
@@ skipping 14 matching lines @@
 
     fileSystem()->createFileWriter(createFileSystemURL(fileEntry), fileWriter.get(), callbacks.release());
     if (errorCode != FileError::OK) {
         FileError::throwDOMException(exceptionState, errorCode);
         return 0;
     }
     return fileWriter.release();
 }
 
 }