Finch kill switch feature for background tab.

chrome/android/java/src/org/chromium/chrome/browser/customtabs/CustomTabsConnection.java

 // Copyright 2015 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.customtabs;
 
 import android.app.ActivityManager;
 import android.app.Application;
 import android.app.PendingIntent;
 import android.content.Context;
@@ skipping 969 matching lines @@
 
     /*
      * This function will do as much as it can to have a subsequent navigation
      * to the specified url sped up.
      */
     private void startSpeculation(CustomTabsSessionToken session, String url, int speculationMode,
             Bundle extras, int uid) {
         WarmupManager warmupManager = WarmupManager.getInstance();
         Profile profile = Profile.getLastUsedProfile();
         boolean preconnect = true, createSpareWebContents = true;
+        if (speculationMode == SpeculationParams.HIDDEN_TAB
+                && !ChromeFeatureList.isEnabled(ChromeFeatureList.CCT_BACKGROUND_TAB)) {
+            speculationMode = SpeculationParams.PRERENDER;
+        }
         switch (speculationMode) {
             case SpeculationParams.PREFETCH:
                 boolean didPrefetch = new ResourcePrefetchPredictor(profile).startPrefetching(url);
                 if (didPrefetch) mSpeculation = SpeculationParams.forPrefetch(session, url);
                 preconnect = !didPrefetch;
                 break;
             case SpeculationParams.PRERENDER:
                 boolean didPrerender = prerenderUrl(session, url, extras, uid);
                 createSpareWebContents = !didPrerender;
                 break;
@@ skipping 123 matching lines @@
      */
     String getReferrer(CustomTabsSessionToken session, Intent intent) {
         String referrer = IntentHandler.getReferrerUrlIncludingExtraHeaders(intent);
         if (referrer == null && getReferrerForSession(session) != null) {
             referrer = getReferrerForSession(session).getUrl();
         }
         if (referrer == null) referrer = "";
         return referrer;
     }
 }