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

chrome/browser/history/most_visited_tiles_experiment.h

+// Copyright (c) 2013 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_HISTORY_MOST_VISITED_TILES_EXPERIMENT_H_
+#define CHROME_BROWSER_HISTORY_MOST_VISITED_TILES_EXPERIMENT_H_
+
+#include "base/values.h"
+#include "chrome/browser/history/history_types.h"
+#include "chrome/common/instant_types.h"
+
+class ListValue;
+class InstantMostVisitedItem;
+
+namespace history {
+
+// 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,
+  // The number of Most Visited Tile Placement experiment actions logged.
+  NUM_NTP_TILE_EXPERIMENT_ACTIONS
+};
+
+// Class for implementing the Most Visited Tile Placement experiment.
+class MostVisitedTilesExperiment {
+ public:
+  // Minimum number of Most Visited suggestions required in order for the Most
+  // Visited Field Trial to remove a URL already open in the browser.
+  static const size_t kMinUrlSuggestions;
+
+  // Name of the histogram tracking types of actions carried out by the Most
+  // Visited Tile Placement experiment.
+  static const char kMostVisitedExperimentHistogramName[];
+
+  // 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 another browser tab are not
+  // displayed on an NTP tile. 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 IsDontShowOpenURLsEnabled();

[Alexei Svitkine (slow), 2013/07/22 21:14:10]

Is there a better name you can come up with for this? This is pretty hard to
read.

For example, IsMostVisitedTilesExperimentEnabled()?

Also, this can be made private if MaybeRemoveMostVisitedItems() is moved to this
file.

[annark1, 2013/07/23 19:52:21]

This name is as per sky@'s suggestion, and is specific to the feature that
doesn't show URLS on the NTP if they're open in the browser, not the experiment.
On 2013/07/22 21:14:10, Alexei Svitkine wrote:

+
+  // Removes URLs already open in browser, for 1993 clients, if part of
+  // experiment described for IsDontShowOpenURLsEnabled().
+  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 IsDontShowOpenURLsEnabled().
+  static void RemovePageValuesMatchingOpenTabs(
+      const std::set<std::string>& open_urls,
+      base::ListValue* pages_value);
+
+ private:
+  // Helper method to log the actions carried out by the Most Visited Tile
+  // Placement experiment.
+  static void LogInHistogram(NtpTileExperimentActions action);
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(MostVisitedTilesExperiment);
+};
+
+}  // namespace history
+
+#endif  // CHROME_BROWSER_HISTORY_MOST_VISITED_TILES_EXPERIMENT_H_