Refactor ResourceHandler API.

content/browser/loader/resource_loader.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_LOADER_RESOURCE_LOADER_H_
 #define CONTENT_BROWSER_LOADER_RESOURCE_LOADER_H_
 
 #include <memory>
 
 #include "base/callback_forward.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time/time.h"
 #include "content/browser/ssl/ssl_client_auth_handler.h"
 #include "content/browser/ssl/ssl_error_handler.h"
 #include "content/common/content_export.h"
-#include "content/public/browser/resource_controller.h"
 #include "net/url_request/url_request.h"
 
 namespace net {
 class X509Certificate;
 }
 
 namespace content {
 class ResourceDispatcherHostLoginDelegate;
 class ResourceHandler;
 class ResourceLoaderDelegate;
 class ResourceRequestInfoImpl;
 
 // This class is responsible for driving the URLRequest (i.e., calling Start,
 // Read, and servicing events).  It has a ResourceHandler, which is typically a
 // chain of ResourceHandlers, and is the ResourceController for its handler.
 class CONTENT_EXPORT ResourceLoader : public net::URLRequest::Delegate,
                                       public SSLErrorHandler::Delegate,
-                                      public SSLClientAuthHandler::Delegate,
-                                      public ResourceController {
+                                      public SSLClientAuthHandler::Delegate {
  public:
   ResourceLoader(std::unique_ptr<net::URLRequest> request,
                  std::unique_ptr<ResourceHandler> handler,
                  ResourceLoaderDelegate* delegate);
   ~ResourceLoader() override;
 
   void StartRequest();
   void CancelRequest(bool from_renderer);
 
   bool is_transferring() const { return is_transferring_; }
   void MarkAsTransferring(const base::Closure& on_transfer_complete_callback);
   void CompleteTransfer();
 
   net::URLRequest* request() { return request_.get(); }
   ResourceRequestInfoImpl* GetRequestInfo();
 
   void ClearLoginDelegate();
 
  private:
+  // ResourceController implementation for the ResourceLoader.
+  class Controller;
+
   // net::URLRequest::Delegate implementation:
   void OnReceivedRedirect(net::URLRequest* request,
                           const net::RedirectInfo& redirect_info,
                           bool* defer) override;
   void OnAuthRequired(net::URLRequest* request,
                       net::AuthChallengeInfo* info) override;
   void OnCertificateRequested(net::URLRequest* request,
                               net::SSLCertRequestInfo* info) override;
   void OnSSLCertificateError(net::URLRequest* request,
                              const net::SSLInfo& info,
                              bool fatal) override;
   void OnResponseStarted(net::URLRequest* request) override;
   void OnReadCompleted(net::URLRequest* request, int bytes_read) override;
 
   // SSLErrorHandler::Delegate implementation:
   void CancelSSLRequest(int error, const net::SSLInfo* ssl_info) override;
   void ContinueSSLRequest() override;
 
   // SSLClientAuthHandler::Delegate implementation.
   void ContinueWithCertificate(net::X509Certificate* cert) override;
   void CancelCertificateSelection() override;
 
-  // ResourceController implementation:
-  void Resume() override;
-  void Cancel() override;
-  void CancelAndIgnore() override;
-  void CancelWithError(int error_code) override;
+  // These correspond to Controller's methods.
+  // TODO(mmenke):  Seems like this could be simplified a little.
+
+  // |is_continuation| is false if called from a ResourceController, and true if
+  // called from ResourceLoader, right after the previous operation succeeded.
+  // In the latter case, the ResourceController's Resume() method was called
+  // synchronously by the ResourceLoader, and the stack has since been unwound,
+  // so the ResourceLoader is at the top of the stack.
+  void Resume(bool is_continuation);
+  void Cancel();
+  void CancelAndIgnore();
+  void CancelWithError(int error_code);
 
   void StartRequestInternal();
   void CancelRequestInternal(int error, bool from_renderer);
   void CompleteResponseStarted();
   void StartReading(bool is_continuation);
   void ResumeReading();
   void ReadMore(int* bytes_read);
   // Passes a read result to the handler.
   void CompleteRead(int bytes_read);
   void ResponseCompleted();
   void CallDidFinishLoading();
   void RecordHistograms();
 
   bool is_deferred() const { return deferred_stage_ != DEFERRED_NONE; }
 
   // Used for categorizing loading of prefetches for reporting in histograms.
   // NOTE: This enumeration is used in histograms, so please do not add entries
   // in the middle.
   enum PrefetchStatus {
     STATUS_UNDEFINED,
     STATUS_SUCCESS_FROM_CACHE,
     STATUS_SUCCESS_FROM_NETWORK,
     STATUS_CANCELED,
     STATUS_MAX,
   };
 
   enum DeferredStage {
     DEFERRED_NONE,
+    // Magic deferral "stage" which means that the code is currently in a
+    // recursive call from the ResourceLoader. When in this state, Resume() does
+    // nothing but update the deferral state, and when the stack is unwound back
+    // up to the ResourceLoader, the request will be continued. This is used to
+    // prevent the stack from getting too deep.
+    DEFERRED_SYNC,
     DEFERRED_START,
     DEFERRED_REDIRECT,
     DEFERRED_READ,
     DEFERRED_RESPONSE_COMPLETE,
     DEFERRED_FINISH
   };
   DeferredStage deferred_stage_;
 
+  class ScopedDeferral;
+
   std::unique_ptr<net::URLRequest> request_;
   std::unique_ptr<ResourceHandler> handler_;
   ResourceLoaderDelegate* delegate_;
 
   scoped_refptr<ResourceDispatcherHostLoginDelegate> login_delegate_;
   std::unique_ptr<SSLClientAuthHandler> ssl_client_auth_handler_;
 
   base::TimeTicks read_deferral_start_time_;
 
   // Indicates that we are in a state of being transferred to a new downstream
@@ skipping 11 matching lines @@
   int times_cancelled_after_request_start_;
 
   base::WeakPtrFactory<ResourceLoader> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ResourceLoader);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_RESOURCE_LOADER_H_