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

chrome/browser/prerender/prerender_local_predictor.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_PRERENDER_PRERENDER_LOCAL_PREDICTOR_H_
 #define CHROME_BROWSER_PRERENDER_PRERENDER_LOCAL_PREDICTOR_H_
 
 #include <vector>
 
 #include "base/hash_tables.h"
 #include "base/memory/weak_ptr.h"
 #include "base/timer.h"
 #include "chrome/browser/common/cancelable_request.h"
 #include "chrome/browser/history/visit_database.h"
 #include "googleurl/src/gurl.h"
 
 class HistoryService;
 
 namespace content {
 class SessionStorageNamespace;
+class WebContents;
 }
 
 namespace gfx {
 class Size;
 }
 
 namespace prerender {
 
 class PrerenderHandle;
 class PrerenderManager;
@@ skipping 46 matching lines @@
     EVENT_CONTINUE_PRERENDER_CHECK_HTTPS = 36,
     EVENT_CONTINUE_PRERENDER_CHECK_ROOT_PAGE = 37,
     EVENT_CONTINUE_PRERENDER_CHECK_LOGOUT_URL = 38,
     EVENT_CONTINUE_PRERENDER_CHECK_LOGIN_URL = 39,
     EVENT_CONTINUE_PRERENDER_CHECK_NOT_LOGGED_IN = 40,
     EVENT_CONTINUE_PRERENDER_CHECK_FALLTHROUGH_NOT_PRERENDERING = 41,
     EVENT_CONTINUE_PRERENDER_CHECK_ISSUING_PRERENDER = 42,
     EVENT_ISSUING_PRERENDER = 43,
     EVENT_NO_PRERENDER_CANDIDATES = 44,
     EVENT_GOT_HISTORY_ISSUING_LOOKUP = 45,
+    EVENT_TAB_HELPER_URL_SEEN = 46,
+    EVENT_TAB_HELPER_URL_SEEN_MATCH = 47,
+    EVENT_TAB_HELPER_URL_SEEN_NAMESPACE_MATCH = 48,
+    EVENT_PRERENDER_URL_LOOKUP_MULTIPLE_SOURCE_WEBCONTENTS_FOUND = 49,
     EVENT_MAX_VALUE
   };
 
   // A PrerenderLocalPredictor is owned by the PrerenderManager specified
   // in the constructor.  It will be destoryed at the time its owning
   // PrerenderManager is destroyed.
   explicit PrerenderLocalPredictor(PrerenderManager* prerender_manager);
   virtual ~PrerenderLocalPredictor();
 
   void Shutdown();
 
   // history::VisitDatabaseObserver implementation
   virtual void OnAddVisit(const history::BriefVisitInfo& info) OVERRIDE;
 
   void OnGetInitialVisitHistory(
       scoped_ptr<std::vector<history::BriefVisitInfo> > visit_history);
 
   void OnPLTEventForURL(const GURL& url, base::TimeDelta page_load_time);
 
+  void OnTabHelperURLSeen(const GURL& url, content::WebContents* web_contents);
+
  private:
   struct PrerenderProperties;
   HistoryService* GetHistoryIfExists() const;
   void Init();
   bool IsPrerenderStillValid(PrerenderProperties* prerender) const;
   bool DoesPrerenderMatchPLTRecord(PrerenderProperties* prerender,
                                    const GURL& url,
                                    base::TimeDelta plt) const;
   void RecordEvent(Event event) const;
 
@@ skipping 32 matching lines @@
   scoped_ptr<PrerenderProperties> current_prerender_;
   scoped_ptr<PrerenderProperties> last_swapped_in_prerender_;
 
   scoped_ptr<PrerenderHandle> prerender_handle_;
   double current_prerender_priority_;
 
   base::hash_set<int64> url_whitelist_;
 
   base::WeakPtrFactory<PrerenderLocalPredictor> weak_factory_;
 
+  // Indicates whether the current prerender represented by prerender_handle_
+  // matched a load in some tab contents, to shed light on how many prerenders
+  // that could have possibily been swapped in were not swapped in. For
+  // measurement purposes only.
+  bool current_prerender_would_have_matched_;
+
   DISALLOW_COPY_AND_ASSIGN(PrerenderLocalPredictor);
 };
 
 }  // namespace prerender
 
 #endif  // CHROME_BROWSER_PRERENDER_PRERENDER_LOCAL_PREDICTOR_H_