Introduce WebSocketHandle and WebSocketHandleClient.

public/platform/Platform.h

Index: public/platform/Platform.h
diff --git a/public/platform/Platform.h b/public/platform/Platform.h
index da4e278ed6b711ec4968dfc8f94f03b469dd9875..a40beac299a193c811563e27ae3f6a53873b16f1 100644
--- a/public/platform/Platform.h
+++ b/public/platform/Platform.h
@@ -80,6 +80,7 @@ class WebPrescientNetworking;
 class WebRTCPeerConnectionHandler;
 class WebRTCPeerConnectionHandlerClient;
 class WebSandboxSupport;
+class WebSocketHandle;
 class WebSocketStreamHandle;
 class WebSpeechSynthesizer;
 class WebSpeechSynthesizerClient;
@@ -302,6 +303,9 @@ public:
     // Returns a new WebSocketStreamHandle instance.
     virtual WebSocketStreamHandle* createSocketStreamHandle() { return 0; }
 
+    // Returns a new WebSocketHandle instance.
+    virtual WebSocketHandle* createWebSocketHandle() { return 0; }
+
     // Returns the User-Agent string that should be used for the given URL.
     virtual WebString userAgent(const WebURL&) { return WebString(); }