Use toDocument instead of static_cast<Document*>.

Source/WebKit/chromium/src/StorageQuotaChromium.cpp

 /*
  * Copyright (C) 2013 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 57 matching lines @@
 void StorageQuota::queryUsageAndQuota(ScriptExecutionContext* scriptExecutionContext, PassRefPtr<StorageUsageCallback> successCallback, PassRefPtr<StorageErrorCallback> errorCallback)
 {
     ASSERT(scriptExecutionContext);
     WebStorageQuotaType storageType = static_cast<WebStorageQuotaType>(m_type);
     if (storageType != WebStorageQuotaTypeTemporary && storageType != WebStorageQuotaTypePersistent) {
         // Unknown storage type is requested.
         scriptExecutionContext->postTask(StorageErrorCallback::CallbackTask::create(errorCallback, NOT_SUPPORTED_ERR));
         return;
     }
     if (scriptExecutionContext->isDocument()) {
-        Document* document = static_cast<Document*>(scriptExecutionContext);
+        Document* document = toDocument(scriptExecutionContext);
         WebFrameImpl* webFrame = WebFrameImpl::fromFrame(document->frame());
         webFrame->client()->queryStorageUsageAndQuota(webFrame, storageType, new WebStorageQuotaCallbacksImpl(successCallback, errorCallback));
     } else {
         WorkerGlobalScope* workerGlobalScope = static_cast<WorkerGlobalScope*>(scriptExecutionContext);
         WebWorkerBase* webWorker = static_cast<WebWorkerBase*>(workerGlobalScope->thread()->workerLoaderProxy().toWebWorkerBase());
         queryUsageAndQuotaFromWorker(webWorker->commonClient(), storageType, new WebStorageQuotaCallbacksImpl(successCallback, errorCallback));
     }
 }
 
 void StorageQuota::requestQuota(ScriptExecutionContext* scriptExecutionContext, unsigned long long newQuotaInBytes, PassRefPtr<StorageQuotaCallback> successCallback, PassRefPtr<StorageErrorCallback> errorCallback)
 {
     ASSERT(scriptExecutionContext);
     WebStorageQuotaType storageType = static_cast<WebStorageQuotaType>(m_type);
     if (storageType != WebStorageQuotaTypeTemporary && storageType != WebStorageQuotaTypePersistent) {
         // Unknown storage type is requested.
         scriptExecutionContext->postTask(StorageErrorCallback::CallbackTask::create(errorCallback, NOT_SUPPORTED_ERR));
         return;
     }
     if (scriptExecutionContext->isDocument()) {
-        Document* document = static_cast<Document*>(scriptExecutionContext);
+        Document* document = toDocument(scriptExecutionContext);
         WebFrameImpl* webFrame = WebFrameImpl::fromFrame(document->frame());
         webFrame->client()->requestStorageQuota(webFrame, storageType, newQuotaInBytes, new WebStorageQuotaCallbacksImpl(successCallback, errorCallback));
     } else {
         // Requesting quota in Worker is not supported.
         scriptExecutionContext->postTask(StorageErrorCallback::CallbackTask::create(errorCallback, NOT_SUPPORTED_ERR));
     }
 }
 
 } // namespace WebCore