Give the main frame a RenderWidget.

content/browser/renderer_host/render_widget_helper.cc

Index: content/browser/renderer_host/render_widget_helper.cc
diff --git a/content/browser/renderer_host/render_widget_helper.cc b/content/browser/renderer_host/render_widget_helper.cc
index 0aad52a6dcbf2ac466a0d85e8f749e7566b45f14..72b2d55ddc93cb27064f17eaf1f2bf5220054bab 100644
--- a/content/browser/renderer_host/render_widget_helper.cc
+++ b/content/browser/renderer_host/render_widget_helper.cc
@@ -102,8 +102,9 @@ void RenderWidgetHelper::CreateNewWindow(
     const ViewHostMsg_CreateWindow_Params& params,
     bool no_javascript_access,
     base::ProcessHandle render_process,
-    int* route_id,
-    int* main_frame_route_id,
+    int32_t* route_id,
+    int32_t* main_frame_route_id,
+    int32_t* main_frame_widget_route_id,
     SessionStorageNamespace* session_storage_namespace) {
   if (params.opener_suppressed || no_javascript_access) {
     // If the opener is supppressed or script access is disallowed, we should
@@ -113,9 +114,14 @@ void RenderWidgetHelper::CreateNewWindow(
     // in OnCreateWindowOnUI, using the params provided here.
     *route_id = MSG_ROUTING_NONE;
     *main_frame_route_id = MSG_ROUTING_NONE;
+    *main_frame_widget_route_id = MSG_ROUTING_NONE;
   } else {
     *route_id = GetNextRoutingID();
     *main_frame_route_id = GetNextRoutingID();
+    // TODO(avi): When RenderViewHostImpl has-a RenderWidgetHostImpl, this
+    // should be updated to give the widget a distinct routing ID.
+    // https://crbug.com/545684
+    *main_frame_widget_route_id = *route_id;
     // Block resource requests until the view is created, since the HWND might
     // be needed if a response ends up creating a plugin.
     resource_dispatcher_host_->BlockRequestsForRoute(
@@ -126,21 +132,23 @@ void RenderWidgetHelper::CreateNewWindow(
 
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
-      base::Bind(&RenderWidgetHelper::OnCreateWindowOnUI,
-                 this, params, *route_id, *main_frame_route_id,
+      base::Bind(&RenderWidgetHelper::OnCreateWindowOnUI, this, params,
+                 *route_id, *main_frame_route_id, *main_frame_widget_route_id,
                  make_scoped_refptr(session_storage_namespace)));
 }
 
 void RenderWidgetHelper::OnCreateWindowOnUI(
     const ViewHostMsg_CreateWindow_Params& params,
-    int route_id,
-    int main_frame_route_id,
+    int32_t route_id,
+    int32_t main_frame_route_id,
+    int32_t main_frame_widget_route_id,
     SessionStorageNamespace* session_storage_namespace) {
   RenderViewHostImpl* host =
       RenderViewHostImpl::FromID(render_process_id_, params.opener_id);
   if (host)
-    host->CreateNewWindow(route_id, main_frame_route_id, params,
-        session_storage_namespace);
+    host->CreateNewWindow(route_id, main_frame_route_id,
+                          main_frame_widget_route_id, params,
+                          session_storage_namespace);
 }
 
 void RenderWidgetHelper::OnResumeRequestsForView(int route_id) {