Add pathway to auto-migrate users when Chrome launches

chrome/android/java/src/org/chromium/chrome/browser/preferences/MainPreferences.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.preferences;
 
 import android.content.Intent;
 import android.os.Bundle;
 import android.os.Handler;
 import android.preference.Preference;
 import android.preference.Preference.OnPreferenceClickListener;
 import android.preference.PreferenceFragment;
 
+import org.chromium.base.ApplicationStatus;
+import org.chromium.base.CommandLine;
 import org.chromium.chrome.R;
+import org.chromium.chrome.browser.ChromeSwitches;
 import org.chromium.chrome.browser.PasswordUIView;
 import org.chromium.chrome.browser.autofill.PersonalDataManager;
 import org.chromium.chrome.browser.net.spdyproxy.DataReductionProxySettings;
 import org.chromium.chrome.browser.partnercustomizations.HomepageManager;
 import org.chromium.chrome.browser.preferences.datareduction.DataReductionPreferences;
 import org.chromium.chrome.browser.signin.AccountSigninActivity;
 import org.chromium.chrome.browser.signin.SigninAccessPoint;
 import org.chromium.chrome.browser.signin.SigninManager;
 import org.chromium.chrome.browser.signin.SigninManager.SignInStateObserver;
 import org.chromium.chrome.browser.util.FeatureUtilities;
@@ skipping 71 matching lines @@
                 }
 
                 mSignInPreference.setEnabled(false);
                 SigninManager.logSigninStartAccessPoint(SigninAccessPoint.SETTINGS);
                 startActivity(new Intent(getActivity(), AccountSigninActivity.class));
                 return true;
             }
         });
         mSignInPreference.setEnabled(true);
 
+        // TODO(dfalcantara): Delete this preference entirely.  https://crbug.com/582539
         Preference documentMode = findPreference(PREF_DOCUMENT_MODE);
-        if (FeatureUtilities.isDocumentModeEligible(getActivity())) {
+        boolean showDocumentToggle = FeatureUtilities.isDocumentModeEligible(getActivity());
+        if (CommandLine.getInstance().hasSwitch(ChromeSwitches.ENABLE_FORCED_MIGRATION)) {
+            showDocumentToggle &=
+                    FeatureUtilities.isDocumentMode(ApplicationStatus.getApplicationContext());
+        }
+        if (showDocumentToggle) {
             setOnOffSummary(documentMode,
                     !DocumentModeManager.getInstance(getActivity()).isOptedOutOfDocumentMode());
         } else {
             getPreferenceScreen().removePreference(documentMode);
         }
 
         ChromeBasePreference autofillPref =
                 (ChromeBasePreference) findPreference(PREF_AUTOFILL_SETTINGS);
         setOnOffSummary(autofillPref, PersonalDataManager.isAutofillEnabled());
         autofillPref.setManagedPreferenceDelegate(mManagedPreferenceDelegate);
@@ skipping 93 matching lines @@
                 if (PREF_DATA_REDUCTION.equals(preference.getKey())) {
                     DataReductionProxySettings settings = DataReductionProxySettings.getInstance();
                     return settings.isDataReductionProxyManaged()
                             && !settings.isDataReductionProxyEnabled();
                 }
                 return super.isPreferenceClickDisabledByPolicy(preference);
             }
         };
     }
 }