Allow prefetches to outlive their owning RenderViewHost.

This is a rework of r231910. Instead of putting the detachable logic in
AsyncResourceHandler, move it to a wrapper DetachableResourceHandler. On
detach, it simulates a cancel to the ResourceHandler it wraps and then
continues to drain the request itself. This should have fewer buffering
complications.

BUG=286186
TEST=ResourceDispatcherHostTest.Cancel,
     ResourceDispatcherHostTest.DetachedResourceTimesOut,
     ResourceDispatcherHostTest.DeletedFilterDetached,
     ResourceDispatcherHostTest.DeletedFilterDetachedRedirect,
     ResourceDispatcherHostTest.DetachWhileStartIsDeferred
     ResourceDispatcherHostTest.TestProcessCancelDetachedTimeout,
     ResourceDispatcherHostTest.CancelRequestsForContextDetached,
     ResourceDispatcherHostTest.DataSentBeforeDetach

Review URL: https://codereview.chromium.org/59783003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236132 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 94 insertions, 0 deletions

diff --git a/content/browser/loader/detachable_resource_handler.h b/content/browser/loader/detachable_resource_handler.h
new file mode 100644
index 0000000..990084d
--- /dev/null
+++ b/content/browser/loader/detachable_resource_handler.h
@@ -0,0 +1,94 @@
+// Copyright 2013 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_DETACHABLE_RESOURCE_HANDLER_H_
+#define CONTENT_BROWSER_LOADER_DETACHABLE_RESOURCE_HANDLER_H_
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/time/time.h"
+#include "base/timer/timer.h"
+#include "content/browser/loader/resource_handler.h"
+#include "content/public/browser/resource_controller.h"
+
+namespace net {
+class IOBuffer;
+class URLRequest;
+}  // namespace net
+
+namespace content {
+
+// A ResourceHandler which delegates all calls to the next handler, unless
+// detached. Once detached, it drives the request to completion itself. This is
+// used for requests which outlive the owning renderer, such as <link
+// rel=prefetch> and <a ping>. Requests do not start out detached so, e.g.,
+// prefetches appear in DevTools and get placed in the renderer's local
+// cache. If the request does not complete after a timeout on detach, it is
+// cancelled.
+//
+// Note that, once detached, the request continues without the original next
+// handler, so any policy decisions in that handler are skipped.
+class DetachableResourceHandler : public ResourceHandler,
+                                  public ResourceController {
+ public:
+  DetachableResourceHandler(net::URLRequest* request,
+                            base::TimeDelta cancel_delay,
+                            scoped_ptr<ResourceHandler> next_handler);
+  virtual ~DetachableResourceHandler();
+
+  bool is_detached() const { return next_handler_ == NULL; }
+  void Detach();
+
+  void set_cancel_delay(base::TimeDelta cancel_delay) {
+    cancel_delay_ = cancel_delay;
+  }
+
+  // ResourceHandler implementation:
+  virtual void SetController(ResourceController* controller) OVERRIDE;
+  virtual bool OnUploadProgress(int request_id, uint64 position,
+                                uint64 size) OVERRIDE;
+  virtual bool OnRequestRedirected(int request_id, const GURL& url,
+                                   ResourceResponse* response,
+                                   bool* defer) OVERRIDE;
+  virtual bool OnResponseStarted(int request_id,
+                                 ResourceResponse* response,
+                                 bool* defer) OVERRIDE;
+  virtual bool OnWillStart(int request_id, const GURL& url,
+                           bool* defer) OVERRIDE;
+  virtual bool OnWillRead(int request_id,
+                          scoped_refptr<net::IOBuffer>* buf,
+                          int* buf_size,
+                          int min_size) OVERRIDE;
+  virtual bool OnReadCompleted(int request_id, int bytes_read,
+                               bool* defer) OVERRIDE;
+  virtual void OnResponseCompleted(int request_id,
+                                   const net::URLRequestStatus& status,
+                                   const std::string& security_info,
+                                   bool* defer) OVERRIDE;
+  virtual void OnDataDownloaded(int request_id, int bytes_downloaded) OVERRIDE;
+
+  // ResourceController implementation:
+  virtual void Resume() OVERRIDE;
+  virtual void Cancel() OVERRIDE;
+  virtual void CancelAndIgnore() OVERRIDE;
+  virtual void CancelWithError(int error_code) OVERRIDE;
+
+ private:
+  scoped_ptr<ResourceHandler> next_handler_;
+  scoped_refptr<net::IOBuffer> read_buffer_;
+
+  scoped_ptr<base::OneShotTimer<DetachableResourceHandler> > detached_timer_;
+  base::TimeDelta cancel_delay_;
+
+  bool is_deferred_;
+  bool is_finished_;
+
+  DISALLOW_COPY_AND_ASSIGN(DetachableResourceHandler);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_LOADER_DETACHABLE_RESOURCE_HANDLER_H_