Signin: Reuse existing "update gms" dialogs when possible.

chrome/android/java/src/org/chromium/chrome/browser/signin/AccountSigninView.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.signin;
 
 import android.app.Activity;
 import android.app.FragmentManager;
 import android.content.Context;
 import android.graphics.Bitmap;
@@ skipping 318 matching lines @@
                         showConfirmSigninPageAccountTrackerServiceCheck();
                     }
                 }
                 callback.onResult(true);
             }
         });
     }
 
     private boolean checkGooglePlayServicesAvailable() {
         ExternalAuthUtils extAuthUtils = ExternalAuthUtils.getInstance();
-        boolean cancelable = !SigninManager.get(getContext()).isForceSigninEnabled();
-        mGooglePlayServicesUpdateErrorHandler = new UserRecoverableErrorHandler.ModalDialog(
-                mDelegate.getActivity(), cancelable);
+        if (mGooglePlayServicesUpdateErrorHandler == null) {
+            boolean cancelable = !SigninManager.get(getContext()).isForceSigninEnabled();
+            mGooglePlayServicesUpdateErrorHandler = new UserRecoverableErrorHandler.ModalDialog(
+                    mDelegate.getActivity(), cancelable);
+        }
         int resultCode = extAuthUtils.canUseGooglePlayServicesResultCode(
                 getContext(), mGooglePlayServicesUpdateErrorHandler);
         if (extAuthUtils.isGooglePlayServicesUpdateRequiredError(resultCode)) {
             mIsGooglePlayServicesOutOfDate = true;
         }
         return resultCode == ConnectionResult.SUCCESS;
     }
 
     /**
      * Attempt to select a new element that is in the new list, but not in the old list.
@@ skipping 268 matching lines @@
      * @return Whether the view is in "no choice, just a confirmation" forced-account mode.
      */
     public boolean isInForcedAccountMode() {
         return mForcedAccountName != null;
     }
 
     private String getSelectedAccountName() {
         return mAccountNames.get(mSigninChooseView.getSelectedAccountPosition());
     }
 }