Add a WebDocument::watchCssSelectors(selectors)

Source/core/loader/FrameLoaderClient.h

Index: Source/core/loader/FrameLoaderClient.h
diff --git a/Source/core/loader/FrameLoaderClient.h b/Source/core/loader/FrameLoaderClient.h
index f02a306c4648a36b2ea62dfda7b8d2e9e9a9c940..5369aea7443bf4cb70ab8a685a43a17f4356c671 100644
--- a/Source/core/loader/FrameLoaderClient.h
+++ b/Source/core/loader/FrameLoaderClient.h
@@ -152,6 +152,10 @@ class FetchRequest;
         virtual void didDetectXSS(const KURL&, bool didBlockEntirePage) = 0;
         virtual void didDispatchPingLoader(const KURL&) = 0;
 
+        // Transmits the change in the set of watched CSS selectors property
+        // that match any element on the frame.
+        virtual void selectorMatchChanged(const Vector<String>& addedSelectors, const Vector<String>& removedSelectors) = 0;
+
         virtual ResourceError interruptedForPolicyChangeError(const ResourceRequest&) = 0;
 
         virtual PassRefPtr<DocumentLoader> createDocumentLoader(const ResourceRequest&, const SubstituteData&) = 0;