Expose WebPageImportanceSignals to embedder

public/web/WebViewClient.h

 /*
  * Copyright (C) 2009 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 97 matching lines @@
     // This method enumerates all the files in the path. It returns immediately
     // and asynchronously invokes the WebFileChooserCompletion with all the
     // files in the directory. Returns false if the WebFileChooserCompletion
     // will never be called.
     virtual bool enumerateChosenDirectory(const WebString& path, WebFileChooserCompletion*) { return false; }
 
     // This method is called in response to WebView's saveImageAt(x, y).
     // A data url from <canvas> or <img> is passed to the method's argument.
     virtual void saveImageFromDataURL(const WebString&) { }
 
+    // Called when PageImportanceSignals for the WebView is updated.
+    virtual void pageImportanceSignalsChanged() { }
+
     // Editing -------------------------------------------------------------
 
     // These methods allow the client to intercept and overrule editing
     // operations.
     virtual void didCancelCompositionOnSelectionChange() { }
     virtual void didChangeContents() { }
 
     // This method is called in response to WebView's handleInputEvent()
     // when the default action for the current keyboard event is not
     // suppressed by the page, to give the embedder a chance to handle
@@ skipping 140 matching lines @@
     // Informs the browser that the draggable regions have been updated.
     virtual void draggableRegionsChanged() { }
 
 protected:
     ~WebViewClient() { }
 };
 
 } // namespace blink
 
 #endif