Use toDocument instead of static_cast<Document*>.

Source/WebKit/chromium/src/LocalFileSystemChromium.cpp

 /*
  * Copyright (C) 2010, 2012 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 139 matching lines @@
 static void deleteFileSystemNotAllowed(ScriptExecutionContext*, PassOwnPtr<AsyncFileSystemCallbacks> callbacks)
 {
     callbacks->didFail(WebKit::WebFileErrorAbort);
 }
 
 static void openFileSystemHelper(ScriptExecutionContext* context, FileSystemType type, PassOwnPtr<AsyncFileSystemCallbacks> callbacks, FileSystemSynchronousType synchronousType, long long size, CreationFlag create)
 {
     bool allowed = true;
     ASSERT(context);
     if (context->isDocument()) {
-        Document* document = static_cast<Document*>(context);
+        Document* document = toDocument(context);
         WebFrameImpl* webFrame = WebFrameImpl::fromFrame(document->frame());
         WebKit::WebViewImpl* webView = webFrame->viewImpl();
         if (webView->permissionClient() && !webView->permissionClient()->allowFileSystem(webFrame))
             allowed = false;
         else
             webFrame->client()->openFileSystem(webFrame, static_cast<WebFileSystemType>(type), size, create == CreateIfNotPresent, new WebFileSystemCallbacksImpl(callbacks));
     } else {
         WorkerGlobalScope* workerGlobalScope = static_cast<WorkerGlobalScope*>(context);
         WebWorkerBase* webWorker = static_cast<WebWorkerBase*>(workerGlobalScope->thread()->workerLoaderProxy().toWebWorkerBase());
         if (!allowFileSystemForWorker())
@@ skipping 16 matching lines @@
 void LocalFileSystem::requestFileSystem(ScriptExecutionContext* context, FileSystemType type, long long size, PassOwnPtr<AsyncFileSystemCallbacks> callbacks, FileSystemSynchronousType synchronousType)
 {
     openFileSystemHelper(context, type, callbacks, synchronousType, size, CreateIfNotPresent);
 }
 
 void LocalFileSystem::deleteFileSystem(ScriptExecutionContext* context, FileSystemType type, PassOwnPtr<AsyncFileSystemCallbacks> callbacks)
 {
     ASSERT(context);
     ASSERT_WITH_SECURITY_IMPLICATION(context->isDocument());
 
-    Document* document = static_cast<Document*>(context);
+    Document* document = toDocument(context);
     WebFrameImpl* webFrame = WebFrameImpl::fromFrame(document->frame());
     WebKit::WebViewImpl* webView = webFrame->viewImpl();
     if (webView->permissionClient() && !webView->permissionClient()->allowFileSystem(webFrame)) {
         context->postTask(createCallbackTask(&deleteFileSystemNotAllowed, callbacks));
         return;
     }
 
     webFrame->client()->deleteFileSystem(webFrame, static_cast<WebFileSystemType>(type), new WebFileSystemCallbacksImpl(callbacks));
 }
 
 } // namespace WebCore