Plumb Push API permission request through Blink using Frame.

public/web/WebFrameClient.h

Index: public/web/WebFrameClient.h
diff --git a/public/web/WebFrameClient.h b/public/web/WebFrameClient.h
index 897ff1cd1808079652ac74e4e64a01ff370d2e60..ac548160e4dc6ac9a803065f82a765b7568c894c 100644
--- a/public/web/WebFrameClient.h
+++ b/public/web/WebFrameClient.h
@@ -57,6 +57,7 @@ namespace blink {
 class WebApplicationCacheHost;
 class WebApplicationCacheHostClient;
 class WebCachedURLRequest;
+class WebCallback;
 class WebColorChooser;
 class WebColorChooserClient;
 class WebContentDecryptionModule;
@@ -325,6 +326,12 @@ public:
     virtual WebNotificationPresenter* notificationPresenter() { return 0; }
 
 
+    // Push API ---------------------------------------------------
+
+    // Requests permission to use the Push API in the origin of this frame.
+    virtual void requestPushPermission(WebCallback* callback) { }
+
+
     // Editing -------------------------------------------------------------
 
     // These methods allow the client to intercept and overrule editing