Clarify when DocumentLoader's FrameLoader/FrameLoaderClient accessors can be used

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

 /*
  * Copyright (C) 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2011 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 42 matching lines @@
 #include "wtf/RefPtr.h"
 #include <memory>
 
 namespace blink {
 
 class ApplicationCacheHost;
 class ResourceFetcher;
 class DocumentInit;
 class LocalFrame;
 class FrameLoader;
+class FrameLoaderClient;
 class ResourceTimingInfo;
 class WebDocumentSubresourceFilter;
 struct ViewportDescriptionWrapper;
 
 class CORE_EXPORT DocumentLoader
     : public GarbageCollectedFinalized<DocumentLoader>,
       private RawResourceClient {
   USING_GARBAGE_COLLECTED_MIXIN(DocumentLoader);
 
  public:
   static DocumentLoader* create(LocalFrame* frame,
                                 const ResourceRequest& request,
                                 const SubstituteData& data,
                                 ClientRedirectPolicy clientRedirectPolicy) {
+    DCHECK(frame);
+
     return new DocumentLoader(frame, request, data, clientRedirectPolicy);
   }
   ~DocumentLoader() override;
 
   LocalFrame* frame() const { return m_frame; }
 
   ResourceTimingInfo* getNavigationTimingInfo() const;
 
   virtual void detachFromFrame();
 
@@ skipping 106 matching lines @@
                                          const AtomicString& mimeType,
                                          const AtomicString& encoding,
                                          bool dispatchWindowObjectAvailable,
                                          ParserSynchronizationPolicy,
                                          const KURL& overridingURL = KURL());
 
   void ensureWriter(const AtomicString& mimeType,
                     const KURL& overridingURL = KURL());
   void endWriting();
 
-  FrameLoader* frameLoader() const;
+  // Use these method only where it's guaranteed that |m_frame| hasn't been
+  // cleared.
+  FrameLoader& frameLoader() const;
+  FrameLoaderClient& frameLoaderClient() const;
 
   void commitIfReady();
   void commitData(const char* bytes, size_t length);
   void clearMainResourceHandle();
 
   bool maybeCreateArchive();
 
   void finishedLoading(double finishTime);
   void cancelLoadAfterCSPDenied(const ResourceResponse&);
+
+  // RawResourceClient implementation
   bool redirectReceived(Resource*,
                         const ResourceRequest&,
                         const ResourceResponse&) final;
   void responseReceived(Resource*,
                         const ResourceResponse&,
                         std::unique_ptr<WebDataConsumerHandle>) final;
   void dataReceived(Resource*, const char* data, size_t length) final;
-  void processData(const char* data, size_t length);
+
+  // ResourceClient implementation
   void notifyFinished(Resource*) final;
   String debugName() const override { return "DocumentLoader"; }
 
+  void processData(const char* data, size_t length);
+
   bool maybeLoadEmpty();
 
   bool isRedirectAfterPost(const ResourceRequest&, const ResourceResponse&);
 
   bool shouldContinueForResponse() const;
 
   Member<LocalFrame> m_frame;
   Member<ResourceFetcher> m_fetcher;
   std::unique_ptr<WebDocumentSubresourceFilter> m_subresourceFilter;
 
@@ skipping 44 matching lines @@
   // Used to protect against reentrancy into dataReceived().
   bool m_inDataReceived;
   RefPtr<SharedBuffer> m_dataBuffer;
 };
 
 DECLARE_WEAK_IDENTIFIER_MAP(DocumentLoader);
 
 }  // namespace blink
 
 #endif  // DocumentLoader_h