Refactor ResourceHandler API.

content/browser/loader/mime_sniffing_resource_handler.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_MIME_SNIFFING_RESOURCE_HANDLER_H_
 #define CONTENT_BROWSER_LOADER_MIME_SNIFFING_RESOURCE_HANDLER_H_
 
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "content/browser/loader/layered_resource_handler.h"
 #include "content/browser/loader/resource_controller.h"
 #include "content/common/content_export.h"
 #include "content/public/common/request_context_type.h"
 #include "ppapi/features/features.h"
 
 namespace net {
 class URLRequest;
 }
 
 namespace content {
 class InterceptingResourceHandler;
 class PluginService;
+class ResourceController;
 class ResourceDispatcherHostImpl;
 struct WebPluginInfo;
 
 // ResourceHandler that, if necessary, buffers a response body without passing
 // it to the next ResourceHandler until it can perform mime sniffing on it.
 //
 // Uses the buffer provided by the original event handler for buffering, and
 // continues to reuses it until it can determine the MIME type
 // subsequent reads until it's done buffering.  As a result, the buffer
 // returned by the next ResourceHandler must have a capacity of at least
 // net::kMaxBytesToSniff * 2.
 //
 // Before a request is sent, this ResourceHandler will also set an appropriate
 // Accept header on the request based on its ResourceType, if one isn't already
 // present.
 class CONTENT_EXPORT MimeSniffingResourceHandler
-    : public LayeredResourceHandler,
-      public ResourceController {
+    : public LayeredResourceHandler {
  public:
   MimeSniffingResourceHandler(std::unique_ptr<ResourceHandler> next_handler,
                               ResourceDispatcherHostImpl* host,
                               PluginService* plugin_service,
                               InterceptingResourceHandler* intercepting_handler,
                               net::URLRequest* request,
                               RequestContextType request_context_type);
   ~MimeSniffingResourceHandler() override;
 
  private:
+  class Controller;
+
   friend class MimeSniffingResourceHandlerTest;
   enum State {
     // Starting state of the MimeSniffingResourceHandler. In this state, it is
     // acting as a blind pass-through ResourceHandler until the response is
     // received.
     STATE_STARTING,
 
     // In this state, the MimeSniffingResourceHandler is buffering the response
     // data in read_buffer_, waiting to sniff the mime type and make a choice
     // about request interception.
     STATE_BUFFERING,
 
     // In this state, the MimeSniffingResourceHandler has identified the mime
     // type and made a decision on whether the request should be intercepted or
     // not. It is nows attempting to replay the response to downstream
     // handlers.
     STATE_INTERCEPTION_CHECK_DONE,
 
     // In this state, the MimeSniffingResourceHandler is replaying the buffered
     // OnResponseStarted event to the downstream ResourceHandlers.
     STATE_REPLAYING_RESPONSE_RECEIVED,
 
     // In this state, the MimeSniffingResourceHandler is just a blind
     // pass-through
     // ResourceHandler.
     STATE_STREAMING,
   };
 
   // ResourceHandler implementation:
-  void SetController(ResourceController* controller) override;
-  bool OnWillStart(const GURL&, bool* defer) override;
-  bool OnResponseStarted(ResourceResponse* response, bool* defer) override;
+  void OnWillStart(const GURL&,
+                   std::unique_ptr<ResourceController> controller) override;
+  void OnResponseStarted(
+      ResourceResponse* response,
+      std::unique_ptr<ResourceController> controller) override;
   bool OnWillRead(scoped_refptr<net::IOBuffer>* buf,
                   int* buf_size,
                   int min_size) override;
-  bool OnReadCompleted(int bytes_read, bool* defer) override;
-  void OnResponseCompleted(const net::URLRequestStatus& status,
-                           bool* defer) override;
+  void OnReadCompleted(int bytes_read,
+                       std::unique_ptr<ResourceController> controller) override;
+  void OnResponseCompleted(
+      const net::URLRequestStatus& status,
+      std::unique_ptr<ResourceController> controller) override;
 
-  // ResourceController implementation:
-  void Resume() override;
-  void Cancel() override;
-  void CancelAndIgnore() override;
-  void CancelWithError(int error_code) override;
+  void ResumeInternal();
 
   // --------------------------------------------------------------------------
   // The following methods replay the buffered data to the downstream
   // ResourceHandlers. They return false if the request should be cancelled,
   // true otherwise. Each of them will set |defer| to true if the request will
   // proceed to the next stage asynchronously.
 
   // Used to advance through the states of the state machine.
   void AdvanceState();
-  bool ProcessState(bool* defer);
 
   // Intercepts the request as a stream/download if needed.
-  bool MaybeIntercept(bool* defer);
+  void MaybeIntercept();
 
   // Replays OnResponseStarted on the downstream handlers.
-  bool ReplayResponseReceived(bool* defer);
+  void ReplayResponseReceived();
 
   // Replays OnReadCompleted on the downstreams handlers.
-  bool ReplayReadCompleted(bool* defer);
+  void ReplayReadCompleted();
 
   // --------------------------------------------------------------------------
 
   // Whether the response body should be sniffed in order to determine the MIME
   // type of the response.
   bool ShouldSniffContent();
 
   // Checks whether this request should be intercepted as a stream or a
   // download. If this is the case, sets up the new ResourceHandler that will be
-  // used for interception. Returns false if teh request should be cancelled,
-  // true otherwise. |defer| is set to true if the interception check needs to
-  // finish asynchronously.
-  bool MaybeStartInterception(bool* defer);
+  // used for interception.
+  //
+  // Returns true on synchronous success, false if the operation will need to
+  // complete asynchronously or failure. On failure, also cancels the request.
+  bool MaybeStartInterception();
 
   // Determines whether a plugin will handle the current request. Returns false
   // if there is an error and the request should be cancelled and true
-  // otherwise. |defer| is set to true if plugin data is stale and needs to be
-  // refreshed before the request can be handled (in this case the function
-  // still returns true). If the request is directed to a plugin,
-  // |handled_by_plugin| is set to true.
-  bool CheckForPluginHandler(bool* defer, bool* handled_by_plugin);
+  // otherwise. If the request is directed to a plugin, |handled_by_plugin| is
+  // set to true.
+  //
+  // Returns true on synchronous success, false if the operation will need to
+  // complete asynchronously or failure. On failure, also cancels the request.
+  bool CheckForPluginHandler(bool* handled_by_plugin);
 
   // Whether this request is allowed to be intercepted as a download or a
   // stream.
   bool CanBeIntercepted();
 
   // Whether the response we received is not provisional.
   bool CheckResponseIsNotProvisional();
 
   bool MustDownload();
 
@@ skipping 15 matching lines @@
   scoped_refptr<net::IOBuffer> read_buffer_;
   int read_buffer_size_;
   int bytes_read_;
 
   // The InterceptingResourceHandler that will perform ResourceHandler swap if
   // needed.
   InterceptingResourceHandler* intercepting_handler_;
 
   RequestContextType request_context_type_;
 
+  // True if current in an AdvanceState loop. Used to prevent re-entrancy and
+  // avoid an extra PostTask.
+  bool in_state_loop_;
+  // Set to true if Resume() is called while |in_state_loop_| is true. When
+  // returning to the parent advance state loop, will synchronously advance to

[Charlie Harrison, 2017/01/25 20:22:59]

s/advance state/AdvanceState for consistency.

[mmenke, 2017/01/25 22:07:59]

Done.

+  // the next state when control returns to the AdvanceState loop.
+  bool advance_state_;
+
   base::WeakPtrFactory<MimeSniffingResourceHandler> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MimeSniffingResourceHandler);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_MIME_SNIFFING_RESOURCE_HANDLER_H_