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 47351ad500112b303adaad83bdc969f0085e3cd3..c6b86ef120ef9cf99e202c21fd9b0775b4dac12b 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 "googleurl/src/gurl.h"
 #include "third_party/skia/include/core/SkColor.h"
@@ -47,6 +48,21 @@ 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.
+  static bool IsClientInTabsGroup();
+
+  // Removes URLs already open in browser, for 1993 clients.
+  static void RemoveItemsMatchingOpenTabs(
+      const std::set<std::string>& open_urls,
+      std::vector<InstantMostVisitedItem>* items);
+
+  // Removes URLs already open in browser, for non-1993 clients.
+  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 +188,18 @@ 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)