Add instrumentation to see how often a local predictor prerender could be

chrome/browser/prerender/prerender_handle.h

Index: chrome/browser/prerender/prerender_handle.h
===================================================================
--- chrome/browser/prerender/prerender_handle.h	(revision 199567)
+++ chrome/browser/prerender/prerender_handle.h	(working copy)
@@ -74,6 +74,11 @@
   // True if we started a prerender, and it has finished loading.
   bool IsFinishedLoading() const;
 
+  // Returns whether the prerender matches the URL provided.
+  bool Matches(
+      const GURL& url,
+      const content::SessionStorageNamespace* session_storage_namespace) const;
+
  private:
   friend class PrerenderManager;