Implement initial part of WebEmbeddedWorker

public/web/WebServiceWorkerContextClient.h

Index: public/web/WebServiceWorkerContextClient.h
diff --git a/public/web/WebServiceWorkerContextClient.h b/public/web/WebServiceWorkerContextClient.h
index 4ee02d16431aa2dc26f6eaea9e63421a24cd38e7..67295e989a05531624627113e96630e4514da051 100644
--- a/public/web/WebServiceWorkerContextClient.h
+++ b/public/web/WebServiceWorkerContextClient.h
@@ -40,10 +40,13 @@ class WebServiceWorkerContextProxy;
 
 // This interface is implemented by the client. It is suppoed to be created
 // on the main thread and then passed on to the worker thread to be owned
-// by a newly created WorkerGlobalScope. All methods of this class are
-// called on the worker thread.
+// by a newly created WorkerGlobalScope. Once workerContextStarted is called
+// (and this should be called first in the normal case) all methods of this

[michaeln, 2013/11/21 02:00:40]

The contract for these callbacks is squishy. It might be nice to tighten that
up.

What if, in the usual case...
  contextStarted()
  contextClosed()  // why is this one needed btw?
  contextDestroyed()
... happen on the worker thread in that order.

And in the early termnination or failed to load the script case...
  contextFailedToStart()
... happens on the main thread and none of the others happen at all.

(nit: Also the verbs used are kind of mixed up, started but never stopped,
closed but never opened, destroyed but never created).

[kinuko, 2013/11/21 06:36:05]

Sounds good, done.
 
Yup, I had the same feeling. These come from existing WorkerGlobalScope /
WorkerReportingProxy verbs, we could reinvent them but I'm not too motivated to
do so for now.

Reg: close perhaps we may be able to live without this exposed at blink API...
removing it for now.  (SWGlobalScope inherits from WGS so app can call close(),
and there's a little period since close() is called and until the WGS is
destroyed. In SharedWorker case we let the browser know about it so that it
doesn't send more messages to the worker)

+// class are called on the worker thread.
 class WebServiceWorkerContextClient {
 public:
+    virtual ~WebServiceWorkerContextClient() { }
+
     // A new WorkerGlobalScope is created and started to run on the
     // worker thread.
     // This also gives back a proxy to the client to talk to the
@@ -57,8 +60,15 @@ public:
 
     // WorkerGlobalScope is destroyed. The client should clear the
     // WebServiceWorkerGlobalScopeProxy when this is called.
+    // This may be called on the main thread before WorkerContextStarted is
+    // called if the worker context is asked to terminate before loading the
+    // script finishes.
     virtual void workerContextDestroyed() { }
 
+    // Loading WorkerGlobalScope is failed. This is called on the main thread
+    // before WorkerContextStarted is called if loading the script fails.
+    virtual void workerContextLoadFailed() { }
+
     virtual void dispatchDevToolsMessage(const WebString&) { }
     virtual void saveDevToolsAgentState(const WebString&) { }
 };