Allows prefetch requests to live beyond the renderer by delaying

content/browser/loader/resource_dispatcher_host_impl.cc

Index: content/browser/loader/resource_dispatcher_host_impl.cc
diff --git a/content/browser/loader/resource_dispatcher_host_impl.cc b/content/browser/loader/resource_dispatcher_host_impl.cc
index 839678e30ce5cc01c6e57f60d725d6ef6e196d1b..b9b1784ffcf4c2876c6b660c37eb64e66531ef44 100644
--- a/content/browser/loader/resource_dispatcher_host_impl.cc
+++ b/content/browser/loader/resource_dispatcher_host_impl.cc
@@ -32,6 +32,7 @@
 #include "content/browser/fileapi/chrome_blob_storage_context.h"
 #include "content/browser/loader/async_resource_handler.h"
 #include "content/browser/loader/buffered_resource_handler.h"
+#include "content/browser/loader/detached_resource_handler.h"
 #include "content/browser/loader/cross_site_resource_handler.h"
 #include "content/browser/loader/power_save_block_resource_throttle.h"
 #include "content/browser/loader/redirect_to_file_resource_handler.h"
@@ -127,6 +128,15 @@ const int kUserGestureWindowMs = 3500;
 // use. Arbitrarily chosen.
 const double kMaxRequestsPerProcessRatio = 0.45;
 
+bool IsDetachableResourceType(const ResourceType::Type type) {
+  switch (type) {
+    case ResourceType::PREFETCH:
+      return true;
+    default:
+      return false;
+  }
+}
+
 // Aborts a request before an URLRequest has actually been created.
 void AbortRequestBeforeItStarts(ResourceMessageFilter* filter,
                                 IPC::Message* sync_result,
@@ -406,13 +416,16 @@ void ResourceDispatcherHostImpl::CancelRequestsForContext(
   for (LoaderList::iterator i = loaders_to_cancel.begin();
        i != loaders_to_cancel.end(); ++i) {
     // There is no strict requirement that this be the case, but currently
-    // downloads, streams  and transferred requests are the only requests that
-    // aren't cancelled when the associated processes go away. It may be OK for
-    // this invariant to change in the future, but if this assertion fires
-    // without the invariant changing, then it's indicative of a leak.
-    DCHECK((*i)->GetRequestInfo()->is_download() ||
-           (*i)->GetRequestInfo()->is_stream() ||
-           (*i)->is_transferring());
+    // downloads, streams, prefetches, and transferred requests are the only
+    // requests that aren't cancelled when the associated processes go away. It
+    // may be OK for this invariant to change in the future, but if this
+    // assertion fires without the invariant changing, then it's indicative of a
+    // leak.
+    DCHECK(
+        (*i)->GetRequestInfo()->is_download() ||
+        (*i)->GetRequestInfo()->is_stream() ||
+        IsDetachableResourceType((*i)->GetRequestInfo()->GetResourceType()) ||
+        (*i)->is_transferring());
   }
 #endif
 
@@ -694,18 +707,21 @@ void ResourceDispatcherHostImpl::DidReceiveRedirect(ResourceLoader* loader,
 
 void ResourceDispatcherHostImpl::DidReceiveResponse(ResourceLoader* loader) {
   ResourceRequestInfoImpl* info = loader->GetRequestInfo();
-  // There should be an entry in the map created when we dispatched the
-  // request.
-  OfflineMap::iterator policy_it(
-      offline_policy_map_.find(info->GetGlobalRoutingID()));
-  if (offline_policy_map_.end() != policy_it) {
-    policy_it->second->UpdateStateForSuccessfullyStartedRequest(
-        loader->request()->response_info());
-  } else {
-    // We should always have an entry in offline_policy_map_ from when
-    // this request traversed Begin{Download,SaveFile,Request}.
-    // TODO(rdsmith): This isn't currently true; see http://crbug.com/241176.
-    NOTREACHED();
+
+  if (!IsDetachableResourceType(info->GetResourceType())) {
+    // There should be an entry in the map created when we dispatched the
+    // request unless it's been detached.

[asanka, 2013/10/11 21:01:20]

This isn't strictly correct, is it? The entry would only be removed if the
associated renderer has died. It's not necessarily true that the entry would be
absent if the request is detachable. This check could prevent
UpdateStateForSuccessfullyStartedRequest() to be called for an entry that
exists.

[jkarlin2, 2013/10/14 14:30:00]

Done.

+    OfflineMap::iterator policy_it(
+        offline_policy_map_.find(info->GetGlobalRoutingID()));
+    if (offline_policy_map_.end() != policy_it) {
+      policy_it->second->UpdateStateForSuccessfullyStartedRequest(
+          loader->request()->response_info());
+    } else {
+      // We should always have an entry in offline_policy_map_ from when
+      // this request traversed Begin{Download,SaveFile,Request}.
+      // TODO(rdsmith): This isn't currently true; see http://crbug.com/241176.
+      NOTREACHED();
+    }
   }
 
   int render_process_id, render_view_id;
@@ -1099,6 +1115,9 @@ void ResourceDispatcherHostImpl::BeginRequest(
   scoped_ptr<ResourceHandler> handler;
   if (sync_result) {
     handler.reset(new SyncResourceHandler(request, sync_result, this));
+  } else if (IsDetachableResourceType(request_data.resource_type)) {
+    // put in detached handler

[asanka, 2013/10/11 21:01:20]

Nit: Remove comment.

[jkarlin2, 2013/10/14 14:30:00]

Done.

+    handler.reset(new DetachedResourceHandler(request, this));
   } else {
     handler.reset(new AsyncResourceHandler(request, this));
   }
@@ -1315,8 +1334,8 @@ void ResourceDispatcherHostImpl::ResumeDeferredNavigation(
 }
 
 // The object died, so cancel and detach all requests associated with it except
-// for downloads, which belong to the browser process even if initiated via a
-// renderer.
+// for downloads and prefetches, which belong to the browser process even if
+// initiated via a renderer.
 void ResourceDispatcherHostImpl::CancelRequestsForProcess(int child_id) {
   CancelRequestsForRoute(child_id, -1 /* cancel all */);
   registered_temp_files_.erase(child_id);
@@ -1341,12 +1360,11 @@ void ResourceDispatcherHostImpl::CancelRequestsForRoute(int child_id,
 
     GlobalRequestID id(child_id, i->first.request_id);
     DCHECK(id == i->first);
-
-    // Don't cancel navigations that are transferring to another process,
-    // since they belong to another process now.
+    // Don't cancel navigations that are expected to live beyond this process.
     if (IsTransferredNavigation(id))
       any_requests_transferring = true;
     if (!info->is_download() && !info->is_stream() &&
+        !IsDetachableResourceType(info->GetResourceType()) &&
         !IsTransferredNavigation(id) &&
         (route_id == -1 || route_id == info->GetRouteID())) {
       matching_requests.push_back(id);