Field trial removing tiles from NTP if URL is already open - for 1993 clients

chrome/browser/history/top_sites.h

Index: chrome/browser/history/top_sites.h
diff --git a/chrome/browser/history/top_sites.h b/chrome/browser/history/top_sites.h
index b55821d34798adb34bb354e4d74308218cc4f691..539a37d14301610d627859db054153bcbb468199 100644
--- a/chrome/browser/history/top_sites.h
+++ b/chrome/browser/history/top_sites.h
@@ -12,6 +12,7 @@
 #include "chrome/browser/common/cancelable_request.h"
 #include "chrome/browser/history/history_service.h"
 #include "chrome/browser/history/history_types.h"
+#include "chrome/common/instant_types.h"
 #include "chrome/common/thumbnail_score.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/image/image.h"
@@ -47,6 +48,27 @@ class TopSites
   // Helper method to shuffle MostVisited tiles for A/B testing purposes.
   static void MaybeShuffle(MostVisitedURLList* data);
 
+  // Returns true if this user is part of the Most Visited Tile Placement
+  // experiment group where URLs currently open in the browser are not displayed
+  // on the NTP. Note: the experiment targets only the top-level of sites i.e.
+  // if www.foo.com/bar is open in browser, and www.foo.com is a recommended
+  // URL, www.foo.com will still appear on the next NTP open. The experiment
+  // will not remove a URL if doing so would cause the number of Most Visited
+  // recommendations to drop below eight.
+  static bool IsClientInTabsGroup();
+
+  // Removes URLs already open in browser, for 1993 clients, if part of
+  // experiment described for IsClientInTabsGroup().
+  static void RemoveItemsMatchingOpenTabs(
+      const std::set<std::string>& open_urls,
+      std::vector<InstantMostVisitedItem>* items);
+
+  // Removes URLs already open in browser, for non-1993 clients, if part of
+  // experiment described for IsClientInTabsGroup().
+  static void RemovePageValuesMatchingOpenTabs(
+      const std::set<std::string>& open_urls,
+      base::ListValue* pages_value);
+
   // Sets the given thumbnail for the given URL. Returns true if the thumbnail
   // was updated. False means either the URL wasn't known to us, or we felt
   // that our current thumbnail was superior to the given one. Should be called
@@ -172,6 +194,18 @@ class TopSites
 
  private:
   friend class base::RefCountedThreadSafe<TopSites>;
+
+  // This enum is also defined in histograms.xml. These values represent the
+  // types of actions carried out by the Most Visited Tile Placement experiment.
+  enum NtpTileExperimentActions {
+    NTP_TILE_EXPERIMENT_ACTION_REMOVED_URL = 0,
+    NTP_TILE_EXPERIMENT_ACTION_DID_NOT_REMOVE_URL = 1,
+    NTP_TILE_EXPERIMENT_ACTION_TOO_FEW_URLS_TILES_1_8 = 2,
+    NTP_TILE_EXPERIMENT_ACTION_TOO_FEW_URLS_TILES_1_4 = 3,
+    NTP_TILE_EXPERIMENT_ACTION_NO_URL_TO_FLIP = 4,
+    // The number of Most Visited Tile Placement experiment actions logged.
+    NUM_NTP_TILE_EXPERIMENT_ACTIONS
+  };
 };
 
 #if defined(OS_ANDROID)