ThreadableLoader::cancel should be called before loader destruction

third_party/WebKit/Source/core/loader/ThreadableLoader.h

 /*
  * Copyright (C) 2009 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 134 matching lines @@
     //   async failures separately
     //
     // Loading completes when one of the following methods are called:
     // - didFinishLoading()
     // - didFail()
     // - didFailAccessControlCheck()
     // - didFailRedirectCheck()
     // After any of these methods is called, the loader won't call any of the
     // ThreadableLoaderClient methods.
     //
-    // When a ThreadableLoader is destructed, any of the
-    // ThreadableLoaderClient methods is NOT called in response to the
-    // destruction either synchronously or after destruction.
+    // A user must guarantee that the loading completes before the attached
+    // client gets invalid. Also, a user must guarantee that the loading
+    // completes before the ThreadableLoader is destructed.
     //
     // When ThreadableLoader::cancel() is called,
     // ThreadableLoaderClient::didFail() is called with a ResourceError
     // with isCancellation() returning true, if any of didFinishLoading()
     // or didFail.*() methods have not been called yet. (didFail() may be
     // called with a ResourceError with isCancellation() returning true
     // also for cancellation happened inside the loader.)
     //
     // ThreadableLoaderClient methods:
     // - may call cancel()
@@ skipping 16 matching lines @@
 
     virtual ~ThreadableLoader() { }
 
 protected:
     ThreadableLoader() { }
 };
 
 } // namespace blink
 
 #endif // ThreadableLoader_h