Move push client to frame.

public/web/WebFrameClient.h

Index: public/web/WebFrameClient.h
diff --git a/public/web/WebFrameClient.h b/public/web/WebFrameClient.h
index 55cd88caae7ff0ff791c331063876afa0afaa20e..553d468605a7a53ecba24173f3fb263c98e2988b 100644
--- a/public/web/WebFrameClient.h
+++ b/public/web/WebFrameClient.h
@@ -78,6 +78,7 @@ class WebSocketHandle;
 class WebNode;
 class WebPlugin;
 class WebPluginPlaceholder;
+class WebPushClient;
 class WebRTCPeerConnectionHandler;
 class WebScreenOrientationClient;
 class WebSharedWorker;
@@ -570,6 +571,10 @@ public:
     // associated with the WebDataSource.
     virtual int64_t serviceWorkerID(WebDataSource&) { return -1; }
 
+    // Push API ------------------------------------------------------------
+
+    virtual WebPushClient* pushClient() { return 0; }
+
 protected:
     virtual ~WebFrameClient() { }
 };