Prevent ThreadableLoaderClient methods from being called after failure notification

Source/core/loader/ThreadableLoader.h

Index: Source/core/loader/ThreadableLoader.h
diff --git a/Source/core/loader/ThreadableLoader.h b/Source/core/loader/ThreadableLoader.h
index e48f842e36da137ccf8d532a5c563034211af258..ad2f652b2fd1626425ad5250d55190cb39fd8872 100644
--- a/Source/core/loader/ThreadableLoader.h
+++ b/Source/core/loader/ThreadableLoader.h
@@ -115,16 +115,25 @@ template<> struct CrossThreadCopierBase<false, false, false, ThreadableLoaderOpt
 
 // Useful for doing loader operations from any thread (not threadsafe,
 // just able to run on threads other than the main thread).
+//
+// Arguments common to both loadResourceSynchronously() and create():
+//
+// - ThreadableLoaderOptions argument configures this ThreadableLoader's
+//   behavior.
+//
+// - ResourceLoaderOptions argument will be passed to the FetchRequest
+//   that this ThreadableLoader creates. It can be altered e.g. when
+//   redirect happens.
 class CORE_EXPORT ThreadableLoader : public RefCounted<ThreadableLoader> {
     WTF_MAKE_NONCOPYABLE(ThreadableLoader);
 public:
-    // ThreadableLoaderOptions argument configures this ThreadableLoader's
-    // behavior.
-    //
-    // ResourceLoaderOptions argument will be passed to the FetchRequest
-    // that this ThreadableLoader creates. It can be altered e.g. when
-    // redirect happens.
     static void loadResourceSynchronously(ExecutionContext&, const ResourceRequest&, ThreadableLoaderClient&, const ThreadableLoaderOptions&, const ResourceLoaderOptions&);
+    // The following ThreadableLoaderClient methods may destroy the
+    // ThreadableLoader instance in them.
+    // - didFinishLoading()
+    // - didFail()
+    // - didFailAccessControlCheck()
+    // - didFailRedirectCheck()

[hiroshige, 2015/08/10 15:15:13]

How about the following?

    // Loading completes when one of the following methods are called:
    // - didFinishLoading()
    // - didFail()
    // - didFailAccessControlCheck()
    // - didFailRedirectCheck()
    // After one of these methods is called, no ThreadableLoaderClient
    // methods are called.
    //
    // When ThreadableLoader is destructed, ThreadableLoaderClient methods
    // are NOT called in response to the destruction or after destruction.
    //
    // When ThreadableLoader::cancel() is called, ThreadableLoaderClient::
    // didFail() is called with ResourceError with isCancellation() is true,
    // if any of didFinishLoading() or didFail.*() methods is not called yet.
    //
    // |ThreadableLoaderClient| methods can call ThreadableLoader::cancel()
    // or can destruct ThreadableLoader by clearing RefPtr<ThreadableLoader>.

[tyoshino (SeeGerritForStatus), 2015/08/26 12:57:33]

Done.

     static PassRefPtr<ThreadableLoader> create(ExecutionContext&, ThreadableLoaderClient*, const ResourceRequest&, const ThreadableLoaderOptions&, const ResourceLoaderOptions&);
 
     // A ThreadableLoader may have a timeout specified. It is possible, in some cases, for