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 6a7b78d5ad8a1d57318d0a219e390e5554370582..b7fdca05518ed5497cc886c7786385ede506e6a2 100644
--- a/content/browser/frame_host/navigator_impl.cc
+++ b/content/browser/frame_host/navigator_impl.cc
@@ -533,7 +533,8 @@ void NavigatorImpl::DidNavigate(
 
     if (!use_site_per_process)
       frame_tree->root()->render_manager()->DidNavigateFrame(
-          render_frame_host, params.gesture == NavigationGestureUser);
+          render_frame_host, params.gesture == NavigationGestureUser,
+          params.was_within_same_page);
   }
 
   // Save the origin of the new page.  Do this before calling
@@ -549,7 +550,8 @@ void NavigatorImpl::DidNavigate(
   if (use_site_per_process) {
     FrameTreeNode* frame = render_frame_host->frame_tree_node();
     frame->render_manager()->DidNavigateFrame(
-        render_frame_host, params.gesture == NavigationGestureUser);
+        render_frame_host, params.gesture == NavigationGestureUser,
+        params.was_within_same_page);
   }
 
   // Update the site of the SiteInstance if it doesn't have one yet, unless
@@ -776,10 +778,12 @@ 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.
-
+  // First start the request on the IO thread.
   navigation_request->BeginNavigation(info.Pass(), params.request_body);
+
+  // Then notify the RenderFrameHostManager so it can speculatively create a
+  // renderer in parallel.
+  frame_tree_node->render_manager()->BeginNavigation(params, common_params);
 }
 
 // PlzNavigate
@@ -820,6 +824,7 @@ void NavigatorImpl::CancelNavigation(FrameTreeNode* frame_tree_node) {
   CHECK(base::CommandLine::ForCurrentProcess()->HasSwitch(
       switches::kEnableBrowserSideNavigation));
   navigation_request_map_.erase(frame_tree_node->frame_tree_node_id());
+  frame_tree_node->render_manager()->CleanUpNavigation();
 }
 
 // PlzNavigate