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 e3b56215d4d26daf3218f1b52f0133bda53ffdc0..efe59f69e5d677fbd1e9775e78066ee7857b0b34 100644
--- a/content/browser/frame_host/navigator_impl.cc
+++ b/content/browser/frame_host/navigator_impl.cc
@@ -738,8 +738,7 @@ 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.
+  frame_tree_node->render_manager()->WillBeginNavigating(params, common_params);

[Charlie Reis, 2014/11/05 17:50:00]

nit: Let's keep with the existing naming scheme to have fewer names to keep
track of.  This should be RFHM::BeginNavigation.

[carlosk, 2014/11/05 20:28:58]

Done.

 
   navigation_request->BeginNavigation(info.Pass(), params.request_body);
 }
@@ -782,6 +781,7 @@ 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()->CleanUpCurrentNavigation();

[Charlie Reis, 2014/11/05 17:50:01]

RFHM::CancelNavigation

[carlosk, 2014/11/05 20:28:58]

Done. I still wanted to have a method to clean-up the speculative data  so I
renamed this one to CleanUpSpeculativeRenderFrameHost, made it private and
created a new one called CancelNavigation that currently just calls the former.

 }
 
 void NavigatorImpl::LogResourceRequestTime(