PlzNavigate: implement process reuse for ServiceWorkers

content/browser/service_worker/service_worker_process_manager.cc

Index: content/browser/service_worker/service_worker_process_manager.cc
diff --git a/content/browser/service_worker/service_worker_process_manager.cc b/content/browser/service_worker/service_worker_process_manager.cc
index 9056e76f03596ef69ab275846ef148da8d92c87c..2ee78caa2f38500ba947ca89a2ddc9a098c16874 100644
--- a/content/browser/service_worker/service_worker_process_manager.cc
+++ b/content/browser/service_worker/service_worker_process_manager.cc
@@ -11,6 +11,7 @@
 
 #include "content/browser/renderer_host/render_process_host_impl.h"
 #include "content/browser/service_worker/service_worker_context_wrapper.h"
+#include "content/browser/site_instance_impl.h"
 #include "content/common/service_worker/embedded_worker_settings.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/content_browser_client.h"
@@ -216,8 +217,11 @@ void ServiceWorkerProcessManager::AllocateWorkerProcess(
   }
 
   // No existing processes available; start a new one.
-  scoped_refptr<SiteInstance> site_instance =
-      SiteInstance::CreateForURL(browser_context_, script_url);
+  scoped_refptr<SiteInstanceImpl> site_instance =
+      SiteInstanceImpl::CreateForURL(browser_context_, script_url);
+  site_instance->set_process_reuse_policy(
+      SiteInstanceImpl::ProcessReusePolicy::
+          REUSE_CHECKING_FRAMES_AND_NAVIGATIONS);

[nasko, 2017/05/05 05:22:00]

Reading this code, I wonder if it will be more natural to pass the policy as
parameter to GetProcess() and it can set it internally.

[clamy, 2017/05/05 15:10:11]

Except it could have already been set in other cases before we get to
GetProcess.

Maybe we could have GetProcessWithReusePolicy(policy) that sets the policy then
does GetProcess?

[Charlie Reis, 2017/05/15 03:41:52]

Just curious, what's the advantage of either of these approaches?  I think
having a separate set_process_reuse_policy seems ok.

[clamy, 2017/05/16 14:50:46]

I'm leaving it as is for now.

   RenderProcessHost* rph = site_instance->GetProcess();
 
   // This Init() call posts a task to the IO thread that adds the RPH's