Drop ntp_snippets::kStudyName in chrome://flags

chrome/android/java/src/org/chromium/chrome/browser/ntp/cards/CardsVariationParameters.java

 // Copyright 2016 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.
 
 package org.chromium.chrome.browser.ntp.cards;
 
 import android.text.TextUtils;
 
 import org.chromium.base.Log;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.components.variations.VariationsAssociatedData;
 
 import java.util.Map;
 
 /**
  * Provides easy access to data for field trials to do with the Cards UI.
  */
 public final class CardsVariationParameters {
     /** Map that stores substitution values for params. */
     private static Map<String, String> sTestVariationParams;
 
     // Tags are limited to 20 characters.
     private static final String TAG = "CardsVariationParams";
 
     // Also defined in ntp_snippets_constants.cc
-    private static final String FIELD_TRIAL_NAME_MAIN = "NTPSnippets";
     private static final String FIELD_TRIAL_NAME_VISIBILITY = "NTPSnippetsVisibility";
 
     private static final String PARAM_FAVICON_SERVICE_NAME = "favicons_fetch_from_service";
     private static final String PARAM_FIRST_CARD_OFFSET = "first_card_offset";
     private static final String PARAM_FIRST_CARD_ANIMATION_MAX_RUNS =
             "first_card_animation_max_runs";
     private static final String PARAM_SCROLL_BELOW_THE_FOLD = "scroll_below_the_fold";
     private static final String PARAM_IGNORE_UPDATES_FOR_EXISTING_SUGGESTIONS =
             "ignore_updates_for_existing_suggestions";
 
     private static final String PARAM_DISABLED_VALUE = "off";
 
     private static final int FIRST_CARD_ANIMATION_DEFAULT_VALUE = 7;
 
+    // TODO(sfiera): replace with feature-specific field trials, as has been done in C++.
+    private static final String FIELD_TRIAL_NAME_MAIN = "NTPSnippets";
+
     private CardsVariationParameters() {}
 
     // TODO(jkrcal): Do a proper general fix in VariationsAssociatedData in the spirit of
     // @Features and ChromeFeatureList.
     /**
      * Sets the parameter values to use in JUnit tests, since native calls are not available there.
      */
     @VisibleForTesting
     public static void setTestVariationParams(Map<String, String> variationParams) {
         sTestVariationParams = variationParams;
@@ skipping 54 matching lines @@
     private static String getParamValue(String fieldTrialName, String paramName) {
         if (sTestVariationParams != null) {
             String value = sTestVariationParams.get(paramName);
             if (value == null) return "";
             return value;
         }
 
         return VariationsAssociatedData.getVariationParamValue(fieldTrialName, paramName);
     }
 }