Add a stub implementation of the URLLoaderFactory for AppCache.

content/browser/loader/navigation_url_loader_network_service.cc

Index: content/browser/loader/navigation_url_loader_network_service.cc
diff --git a/content/browser/loader/navigation_url_loader_network_service.cc b/content/browser/loader/navigation_url_loader_network_service.cc
index f7d814d7f136aa336bfd55720a1cb4967237c4fe..dac8ea52b916e62fe20c87743de358a390041832 100644
--- a/content/browser/loader/navigation_url_loader_network_service.cc
+++ b/content/browser/loader/navigation_url_loader_network_service.cc
@@ -9,8 +9,6 @@
 #include "base/memory/ptr_util.h"
 #include "base/trace_event/trace_event.h"
 #include "content/browser/appcache/appcache_navigation_handle.h"
-#include "content/browser/appcache/appcache_navigation_handle_core.h"
-#include "content/browser/appcache/appcache_request_handler.h"
 #include "content/browser/blob_storage/chrome_blob_storage_context.h"
 #include "content/browser/frame_host/frame_tree_node.h"
 #include "content/browser/frame_host/navigation_request_info.h"
@@ -93,20 +91,6 @@ void PrepareNavigationStartOnIO(
             request_info->common_params.post_data, web_contents_getter);
   }
 
-  // TODO(scottmg): We need to rework AppCache to have it return a
-  // URLLoaderFactoryPtr[Info] here. We should also try to have it return
-  // synchronously in as many cases as possible (especially when there's no
-  // AppCache) to simplify and speed the common case.
-  if (false /*appcache_handle_core*/) {
-    AppCacheRequestHandler::InitializeForNavigationNetworkService(
-        std::move(resource_request), resource_context, appcache_handle_core,
-        resource_type,
-        base::Callback<void(
-            mojom::URLLoaderFactoryPtrInfo,
-            std::unique_ptr<ResourceRequest>)>() /* TODO(ananta) */);
-    return;
-  }
-
   // If we haven't gotten one from the above, then use the one the UI thread
   // gave us, or otherwise fallback to the default.
   mojom::URLLoaderFactory* factory;
@@ -117,7 +101,11 @@ void PrepareNavigationStartOnIO(
       url_loader_factory_ptr.Bind(std::move(factory_from_ui));
       factory = url_loader_factory_ptr.get();
     } else {
-      factory = url_loader_factory_getter->GetNetworkFactory()->get();
+      if (appcache_handle_core) {

[jam, 2017/05/17 16:51:12]

doesn't have to be here, but we should really only be calling to appcache
asynchronously if there's a chance that there's an appcache.

can we change the appcache interface so that it can return synchronously when
the in-memory data structure doesn't have an entry for that origin?

[ananta, 2017/05/17 18:14:09]

That is going to be touch tricky to do at the moment. Plan to revisit this once
the pieces fall into place.

[ananta, 2017/05/17 20:45:27]

Scratch that. I added code in the AppCacheURLLoader to call the network service
if we don't find the origin in the usage map.

+        factory = url_loader_factory_getter->GetAppCacheFactory()->get();

[kinuko, 2017/05/17 16:54:30]

So we almost always take this path after this patch lands.

[ananta, 2017/05/17 18:14:09]

Yes.

+      } else {
+        factory = url_loader_factory_getter->GetNetworkFactory()->get();
+      }
     }
   }