Refactor ResourceHandler API.

content/browser/loader/intercepting_resource_handler.h

 // Copyright 2016 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_INTERCEPTING_RESOURCE_HANDLER_H_
 #define CONTENT_BROWSER_LOADER_INTERCEPTING_RESOURCE_HANDLER_H_
 
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "content/browser/loader/layered_resource_handler.h"
 #include "content/browser/loader/resource_controller.h"
 #include "content/browser/loader/resource_handler.h"
 #include "content/common/content_export.h"
 #include "net/base/io_buffer.h"
 #include "net/url_request/url_request_status.h"
 
 namespace net {
 class URLRequest;
 }
 
 namespace content {
 
+class ResourceController;
+
 // ResourceHandler that initiates special handling of the response if needed,
 // based on the response's MIME type (starts downloads, sends data to some
 // plugin types via a special channel).
 //
 // An InterceptingResourceHandler holds two handlers (|next_handler| and
 // |new_handler|). It assumes the following:
 //  - OnResponseStarted on |next_handler| never sets |*defer|.
 //  - OnResponseCompleted on |next_handler| never sets |*defer|.
 class CONTENT_EXPORT InterceptingResourceHandler
-    : public LayeredResourceHandler,
-      public ResourceController {
+    : public LayeredResourceHandler {
  public:
   InterceptingResourceHandler(std::unique_ptr<ResourceHandler> next_handler,
                               net::URLRequest* request);
   ~InterceptingResourceHandler() override;
 
   // ResourceHandler implementation:
-  void SetController(ResourceController* controller) override;
-  bool OnResponseStarted(ResourceResponse* response, bool* defer) 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 Cancel() override;
-  void CancelAndIgnore() override;
-  void CancelWithError(int error_code) override;
-  void Resume() override;
+  void ResumeInternal();

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

Not part of ResourceHandler implementation, add newline above.

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

There is already one, actually.  I went ahead and made this private, though (Not
sure why I didn't make it private in the first place)

 
   // Replaces the next handler with |new_handler|, sending
   // |payload_for_old_handler| to the old handler. Must be called after
   // OnWillStart and OnRequestRedirected and before OnResponseStarted. One
   // OnWillRead call is permitted beforehand. |new_handler|'s OnWillStart and
   // OnRequestRedirected methods will not be called.
   void UseNewHandler(std::unique_ptr<ResourceHandler> new_handler,
                      const std::string& payload_for_old_handler);
 
   // Used in tests.
   ResourceHandler* new_handler_for_testing() const {
     return new_handler_.get();
   }
 
  private:
+  // ResourceController subclass that calls into the InterceptingResourceHandler
+  // on cancel/resume.
+  class Controller;
+
   enum class State {
     // The InterceptingResourceHandler is waiting for the mime type of the
     // response to be identified, to check if the next handler should be
     // replaced with an appropriate one.
     STARTING,
 
+    // The InterceptingResourceHandler is starting the process of swapping
+    // handlers.
+    SWAPPING_HANDLERS,
+
     // The InterceptingResourceHandler is sending the payload given via
     // UseNewHandler to the old handler and waiting for its completion via
     // Resume().
     SENDING_PAYLOAD_TO_OLD_HANDLER,
 
     // The InterceptingResourcHandler is calling the new handler's
     // OnResponseStarted method and waiting for its completion via Resume().
     // After completion, the InterceptingResourceHandler will transition to
     // SENDING_ON_RESPONSE_STARTED_TO_NEW_HANDLER on success.
     SENDING_ON_WILL_START_TO_NEW_HANDLER,
@@ skipping 12 matching lines @@
     // the new handler and waiting for its completion via Resume().
     SENDING_BUFFER_TO_NEW_HANDLER,
 
     // The InterceptingResourceHandler has replaced its next ResourceHandler if
     // needed, and has ensured the buffered read data was properly transmitted
     // to the new ResourceHandler. The InterceptingResourceHandler now acts as
     // a pass-through ResourceHandler.
     PASS_THROUGH,
   };
 
-  // Runs necessary operations depending on |state_|. Returns false when an
-  // error happens, and set |*defer| to true if the operation continues upon
-  // return.
-  bool DoLoop(bool* defer);
+  // Runs necessary operations depending on |state_|.
+  void DoLoop();
 
-  // The return value and |defer| has the same meaning as DoLoop.
-  bool SendPayloadToOldHandler(bool* defer);
-  bool SendFirstReadBufferToNewHandler(bool* defer);
-  bool SendOnResponseStartedToNewHandler(bool* defer);
-
-  // Wraps calls to DoLoop. Resumes or Cancels underlying request, if needed.
-  void AdvanceState();
+  void SendOnResponseStartedToOldHandler();
+  void SendPayloadToOldHandler();
+  void SendFirstReadBufferToNewHandler();
+  void SendOnResponseStartedToNewHandler();
 
   State state_ = State::STARTING;
 
   std::unique_ptr<ResourceHandler> new_handler_;
   std::string payload_for_old_handler_;
   size_t payload_bytes_written_ = 0;
 
   // Result of the first read, that may have to be passed to an alternate
   // ResourceHandler instead of the original ResourceHandler.
   scoped_refptr<net::IOBuffer> first_read_buffer_;
   // Instead of |first_read_buffer_|, this handler creates a new IOBuffer with
   // the same size and return it to the client.
   scoped_refptr<net::IOBuffer> first_read_buffer_double_;
   size_t first_read_buffer_size_ = 0;
   size_t first_read_buffer_bytes_read_ = 0;
   size_t first_read_buffer_bytes_written_ = 0;
 
   scoped_refptr<ResourceResponse> response_;
 
+  // Next two values are used to handle synchronous Resume calls without a
+  // PostTask.
+
+  // True if the code is currently withing a DoLoop.

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

s/withing/within

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

Done.

+  bool in_do_loop_ = false;
+  // True if the request was resumed while |in_do_loop_| was true;
+  bool advance_to_next_state_ = false;
+
   base::WeakPtrFactory<InterceptingResourceHandler> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(InterceptingResourceHandler);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_LOADER_INTERCEPTING_RESOURCE_HANDLER_H_