PlzNavigate: Speculatively spawns a renderer process for navigations.

content/browser/frame_host/navigator_impl.cc

Index: content/browser/frame_host/navigator_impl.cc
diff --git a/content/browser/frame_host/navigator_impl.cc b/content/browser/frame_host/navigator_impl.cc
index 39956621dfd5f5cfadb5b0ad0fe123726f7e58ce..1b9711ff6976c76e6165e925753bbc796e95cb6d 100644
--- a/content/browser/frame_host/navigator_impl.cc
+++ b/content/browser/frame_host/navigator_impl.cc
@@ -754,10 +754,9 @@ void NavigatorImpl::OnBeginNavigation(
   info->parent_is_main_frame = !frame_tree_node->parent() ?
       false : frame_tree_node->parent()->IsMainFrame();
 
-  // TODO(clamy): Inform the RenderFrameHostManager that a navigation is about
-  // to begin, so that it can speculatively spawn a new renderer if needed.
-
   navigation_request->BeginNavigation(info.Pass(), params.request_body);
+
+  frame_tree_node->render_manager()->BeginNavigation(params, common_params);
 }
 
 // PlzNavigate
@@ -798,6 +797,7 @@ void NavigatorImpl::CancelNavigation(FrameTreeNode* frame_tree_node) {
   CHECK(CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kEnableBrowserSideNavigation));
   navigation_request_map_.erase(frame_tree_node->frame_tree_node_id());
+  frame_tree_node->render_manager()->CleanUpNavigation();
 }
 
 // PlzNavigate