Add blink-side plumbing for ServiceWorker -> Document postMessage (1/3)

public/platform/WebServiceWorkerProviderClient.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 13 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef WebServiceWorkerProviderClient_h
 #define WebServiceWorkerProviderClient_h
 
+#include "public/platform/WebMessagePortChannel.h"
+
 namespace blink {
 class WebServiceWorker;
 class WebString;
 
 // This class provides interface for embedders to talk to

[jsbell, 2014/05/05 19:03:05]

Since this is for embedders to talk to Blink, this class should be in public/web
rather than public/platform, shouldn't it? Which would imply an extra a level of
indirection in the impl.
 

[kinuko, 2014/05/05 23:26:02]

I think we already have multiple interfaces in public/platform that work in this
way, e.g. WebMessagePortChannelClient, WebSocketStreamHandleClient etc, and
public/{platform, web} distinction should be made based on layering rather than
by direction?

[jsbell, 2014/05/06 00:05:21]

Yeah, direction's not important. But the concrete implementation of 
public/platform/* is usually in Chromium (content/child or content/renderer),
whereas the concrete implementation of public/web/* is usually in WebKit
(Source/web).

(I'd push forward as-is and clean up later, just thought I'd point this out. As
usual, I'm happy to be corrected!)

 // ServiceWorkerContainer.
 class WebServiceWorkerProviderClient {
 public:
     virtual ~WebServiceWorkerProviderClient() { }
 
     // The callee will take ownership of the given WebServiceWorker object.
     virtual void setCurrentServiceWorker(WebServiceWorker*) = 0;
+
+    virtual void dispatchMessageEvent(const WebString& message, const WebMessagePortChannelArray&) = 0;
 };
 
 };
 
 #endif // WebServiceWorkerProviderClient_h