Allows prefetch requests to live beyond the renderer by delaying

content/browser/loader/resource_loader.cc

Index: content/browser/loader/resource_loader.cc
diff --git a/content/browser/loader/resource_loader.cc b/content/browser/loader/resource_loader.cc
index 846ad31521d1a3e0af1aa4b899b0a5cefc6a8f4f..a9952599c2aab194134aacb92aae45017e1f2757 100644
--- a/content/browser/loader/resource_loader.cc
+++ b/content/browser/loader/resource_loader.cc
@@ -7,7 +7,9 @@
 #include "base/command_line.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/histogram.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/time/time.h"
+#include "base/timer/timer.h"
 #include "content/browser/child_process_security_policy_impl.h"
 #include "content/browser/loader/cross_site_resource_handler.h"
 #include "content/browser/loader/resource_loader_delegate.h"
@@ -36,6 +38,13 @@ using base::TimeTicks;
 namespace content {
 namespace {
 
+// TODO(jkarlin): The value is high to reduce the chance of the detachable
+// request timing out, forcing a blocked second request to open a new connection
+// and start over. Reduce this value once we have a better idea of what it
+// should be and once we stop blocking multiple simultaneous requests for the
+// same resource (see bugs 46104 and 31014).
+const int kDefaultDetachableDelayOnCancelMs = 30000;
+
 void PopulateResourceResponse(net::URLRequest* request,
                               ResourceResponse* response) {
   response->head.error_code = request->status().error();
@@ -74,6 +83,7 @@ ResourceLoader::ResourceLoader(scoped_ptr<net::URLRequest> request,
       last_upload_position_(0),
       waiting_for_upload_progress_ack_(false),
       is_transferring_(false),
+      detachable_delay_on_cancel_ms_(kDefaultDetachableDelayOnCancelMs),
       weak_ptr_factory_(this) {
   request_->set_delegate(this);
   handler_->SetController(this);
@@ -429,6 +439,18 @@ void ResourceLoader::StartRequestInternal() {
   delegate_->DidStartRequest(this);
 }
 
+void ResourceLoader::Detach() {
+  ResourceRequestInfoImpl* info = GetRequestInfo();
+
+  if (info->is_detached())
+    return;
+  info->set_detached();
+  detached_timer_.reset(new base::OneShotTimer<ResourceLoader>());
+  detached_timer_->Start(
+      FROM_HERE, TimeDelta::FromMilliseconds(detachable_delay_on_cancel_ms_),
+      this, &ResourceLoader::Cancel);
+}
+
 void ResourceLoader::CancelRequestInternal(int error, bool from_renderer) {
   VLOG(1) << "CancelRequestInternal: " << request_->url().spec();
 
@@ -440,6 +462,11 @@ void ResourceLoader::CancelRequestInternal(int error, bool from_renderer) {
   if (from_renderer && (info->is_download() || info->is_stream()))
     return;
 
+  if (from_renderer && info->is_detachable()) {
+    Detach();
+    return;
+  }
+
   // TODO(darin): Perhaps we should really be looking to see if the status is
   // IO_PENDING?
   bool was_pending = request_->is_pending();