Allows prefetch requests to live beyond the renderer by delaying

content/browser/loader/resource_loader.cc

 // 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.
 
 #include "content/browser/loader/resource_loader.h"
 
 #include "base/command_line.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram.h"
 #include "base/time/time.h"
+#include "base/timer/timer.h"
 #include "content/browser/child_process_security_policy_impl.h"
 #include "content/browser/loader/resource_loader_delegate.h"
 #include "content/browser/loader/resource_request_info_impl.h"
 #include "content/browser/ssl/ssl_client_auth_handler.h"
 #include "content/browser/ssl/ssl_manager.h"
 #include "content/common/ssl_status_serialization.h"
 #include "content/public/browser/cert_store.h"
 #include "content/public/browser/resource_dispatcher_host_login_delegate.h"
 #include "content/public/browser/site_instance.h"
 #include "content/public/common/content_client.h"
@@ skipping 34 matching lines @@
       request,
       &response->head.appcache_id,
       &response->head.appcache_manifest_url);
   // TODO(mmenke):  Figure out if LOAD_ENABLE_LOAD_TIMING is safe to remove.
   if (request->load_flags() & net::LOAD_ENABLE_LOAD_TIMING)
     request->GetLoadTimingInfo(&response->head.load_timing);
 }
 
 }  // namespace
 
+int ResourceLoader::delay_prefetch_cancel_ms_ = 60000;
+
 ResourceLoader::ResourceLoader(scoped_ptr<net::URLRequest> request,
                                scoped_ptr<ResourceHandler> handler,
                                ResourceLoaderDelegate* delegate)
     : weak_ptr_factory_(this) {
   scoped_ptr<net::ClientCertStore> client_cert_store;
 #if !defined(USE_OPENSSL)
   client_cert_store.reset(new net::ClientCertStoreImpl());
 #endif
   Init(request.Pass(), handler.Pass(), delegate, client_cert_store.Pass());
 }
@@ skipping 385 matching lines @@
   VLOG(1) << "CancelRequestInternal: " << request_->url().spec();
 
   ResourceRequestInfoImpl* info = GetRequestInfo();
 
   // WebKit will send us a cancel for downloads since it no longer handles
   // them.  In this case, ignore the cancel since we handle downloads in the
   // browser.
   if (from_renderer && (info->is_download() || info->is_stream()))
     return;
 
+  // Delay requests to cancel prefetches
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
+  if (from_renderer &&
+      command_line.HasSwitch(switches::kDelayPrefetchCancellation) &&
+      info->GetResourceType() == ResourceType::PREFETCH) {
+    if (prefetch_timer_.get() && prefetch_timer_->IsRunning()) {
+      // We've already processed a cancel for this prefetch, ignore this cancel.
+      return;
+    } else if (!prefetch_timer_.get()) {
+      // Our first call to cancel this prefetch, start a delay timer.
+      prefetch_timer_.reset(new base::OneShotTimer<ResourceLoader>());
+      prefetch_timer_->Start(
+          FROM_HERE, TimeDelta::FromMilliseconds(delay_prefetch_cancel_ms_),
+          this, &ResourceLoader::Cancel);
+      return;
+    }  // else we have an expired delay timer, cancel the load.
+  }
+
   // TODO(darin): Perhaps we should really be looking to see if the status is
   // IO_PENDING?
   bool was_pending = request_->is_pending();
 
   if (login_delegate_.get()) {
     login_delegate_->OnRequestCancelled();
     login_delegate_ = NULL;
   }
   if (ssl_client_auth_handler_.get()) {
     ssl_client_auth_handler_->OnRequestCancelled();
@@ skipping 168 matching lines @@
     // we resume.
     deferred_stage_ = DEFERRED_FINISH;
   }
 }
 
 void ResourceLoader::CallDidFinishLoading() {
   delegate_->DidFinishLoading(this);
 }
 
 }  // namespace content