Add IncrementWorkerRefCount() and DecrementWorkerRefCount() to RenderProcessHostImpl.

content/public/browser/render_process_host.h

Index: content/public/browser/render_process_host.h
diff --git a/content/public/browser/render_process_host.h b/content/public/browser/render_process_host.h
index a259f6db667330c28729c7bea8657022b998e16c..356aa07bce3cf087fa2cd7f783ced37d98c88b51 100644
--- a/content/public/browser/render_process_host.h
+++ b/content/public/browser/render_process_host.h
@@ -228,6 +228,11 @@ class CONTENT_EXPORT RenderProcessHost : public IPC::Sender,
   // transferring it to a new renderer process.
   virtual void ResumeDeferredNavigation(const GlobalRequestID& request_id) = 0;
 
+  // Called when the existance of the other renderer process which is connected
+  // to the SharedWorker in this renderer process has changed.
+  // It is only called when "enable-embedded-shared-worker" flag is set.
+  virtual void SetExternalClientStatus(bool has_external_worker_client) = 0;

[kinuko, 2014/03/04 04:48:48]

Does this need to be exposed at content/public?  The caller of this method will
be in content/ too, right?

Also a few comments:

The naming feels a bit vague to me while the comment gives very specific usage--
why it's called external client?

Also passing a single true/false boolean value seems to assume we have a single
caller for this method, while the method name is made somewhat generic.  Could
this be a pair of Add*/Remove* methods? (Then ServiceWorker could probably use
the same method)

[horo, 2014/03/04 06:40:43]

Changed to RenderProcessHostImpl::SetHasExternalWorkerClient(bool
has_external_worker_client).

This method is only called only from SharedWorkerServiceImpl which manages
SharedWorkers.
So I think SetHasExternalWorkerClient() is better than AddExternalWorker() and
RemoveExternalWorker().

[kinuko, 2014/03/04 06:58:46]

(As we talked offline) If this is specifically for SharedWorker can we name this
explicitly specific to SharedWorker? (E.g. SetHasRunningSharedWorker or
NotifySharedWorkerHasClients etc)  Otherwise I want to reuse this for
ServiceWorker too, and would it be in the Add/Remove format.

+
   // Static management functions -----------------------------------------------
 
   // Flag to run the renderer in process.  This is primarily