Revert the merge of CrossSiteResourceHandler and NavigationResourceThrottle.

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 f2c1ac98e8cd6387941ada630c8b712ed8d68600..8cc50c6f05820225092b7d051a9878edc962c5ee 100644
--- a/content/browser/loader/resource_dispatcher_host_impl.cc
+++ b/content/browser/loader/resource_dispatcher_host_impl.cc
@@ -44,6 +44,7 @@
 #include "content/browser/frame_host/navigator.h"
 #include "content/browser/loader/async_resource_handler.h"
 #include "content/browser/loader/async_revalidation_manager.h"
+#include "content/browser/loader/cross_site_resource_handler.h"
 #include "content/browser/loader/detachable_resource_handler.h"
 #include "content/browser/loader/intercepting_resource_handler.h"
 #include "content/browser/loader/loader_delegate.h"
@@ -1172,6 +1173,9 @@ void ResourceDispatcherHostImpl::UpdateRequestForTransfer(
           child_id, request_data.service_worker_provider_id);
     }
   }
+
+  // We should have a CrossSiteResourceHandler to finish the transfer.
+  DCHECK(info->cross_site_handler());
 }
 
 void ResourceDispatcherHostImpl::BeginRequest(
@@ -1577,6 +1581,28 @@ ResourceDispatcherHostImpl::CreateResourceHandler(
     handler = std::move(detachable_handler);
   }
 
+  // PlzNavigate: If using --enable-browser-side-navigation, the
+  // CrossSiteResourceHandler is not needed. This codepath is not used for the
+  // actual navigation request, but only the subsequent blob URL load. This does
+  // not require request transfers.
+  if (!IsBrowserSideNavigationEnabled()) {
+    // Install a CrossSiteResourceHandler for all main frame requests. This will
+    // check whether a transfer is required and, if so, pause for the UI thread
+    // to drive the transfer.
+    bool is_swappable_navigation =
+        request_data.resource_type == RESOURCE_TYPE_MAIN_FRAME;
+    // If out-of-process iframes are possible, then all subframe requests need
+    // to go through the CrossSiteResourceHandler to enforce the site isolation
+    // policy.
+    if (!is_swappable_navigation &&
+        SiteIsolationPolicy::AreCrossProcessFramesPossible()) {
+      is_swappable_navigation =
+          request_data.resource_type == RESOURCE_TYPE_SUB_FRAME;
+    }
+    if (is_swappable_navigation && process_type == PROCESS_TYPE_RENDERER)
+      handler.reset(new CrossSiteResourceHandler(std::move(handler), request));
+  }
+
   return AddStandardHandlers(
       request, request_data.resource_type, resource_context,
       request_data.fetch_request_context_type, filter_->appcache_service(),
@@ -1822,8 +1848,8 @@ void ResourceDispatcherHostImpl::OnRenderViewHostSetIsLoading(int child_id,
 
 void ResourceDispatcherHostImpl::MarkAsTransferredNavigation(
     const GlobalRequestID& id,
-    const base::Closure& on_transfer_complete_callback) {
-  GetLoader(id)->MarkAsTransferring(on_transfer_complete_callback);
+    const scoped_refptr<ResourceResponse>& response) {
+  GetLoader(id)->MarkAsTransferring(response);
 }
 
 void ResourceDispatcherHostImpl::CancelTransferringNavigation(