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 c99fe5b0d7cd36eb1f45ac2464bdc287ffef3b73..270cbf0b8f5e1ce92797b6fe4d68c03e23cd5116 100644
--- a/content/browser/loader/resource_loader.cc
+++ b/content/browser/loader/resource_loader.cc
@@ -8,6 +8,7 @@
 #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"
@@ -62,6 +63,8 @@ void PopulateResourceResponse(net::URLRequest* request,
 
 }  // namespace
 
+int ResourceLoader::delay_prefetch_cancel_ms_ = 60000;
+
 ResourceLoader::ResourceLoader(scoped_ptr<net::URLRequest> request,
                                scoped_ptr<ResourceHandler> handler,
                                ResourceLoaderDelegate* delegate)
@@ -467,6 +470,24 @@ void ResourceLoader::CancelRequestInternal(int error, bool from_renderer) {
   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();