[Android] Add wrapper to get AuthenticatorNavigationInterceptor

The APIs via which AuthenticatorNavigationInterceptor instances are
obtained from Tabs are currently being refactored. However, those APIs
are used downstream. To allow those refactorings to proceed without
breaking downstream this CL introduces an
AuthenticatorNavigationInterceptorTabHelper wrapper that downstream can
use to be isolated from the specific APIs being refactored. I will
delete this wrapper once the upstream refactorings have landed and I
have converted downstream to use them.

Bug: 1031465
Change-Id: I232e785674d155d16b968c8d91889df6c73b7ebc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2142257Reviewed-by: Michael Thiessen <mthiesse@chromium.org>
Commit-Queue: Colin Blundell <blundell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#757760}

chrome/android/chrome_java_sources.gni

@@ -1571,6 +1571,7 @@ chrome_java_sources = [
   "java/src/org/chromium/chrome/browser/sync/ui/PassphraseTypeDialogFragment.java",
   "java/src/org/chromium/chrome/browser/tab/AccessibilityVisibilityHandler.java",
   "java/src/org/chromium/chrome/browser/tab/AuthenticatorNavigationInterceptor.java",
+  "java/src/org/chromium/chrome/browser/tab/AuthenticatorNavigationInterceptorTabHelper.java",
   "java/src/org/chromium/chrome/browser/tab/EmptyTabObserver.java",
   "java/src/org/chromium/chrome/browser/tab/InterceptNavigationDelegateImpl.java",
   "java/src/org/chromium/chrome/browser/tab/RedirectHandlerTabHelper.java",

chrome/android/java/src/org/chromium/chrome/browser/tab/AuthenticatorNavigationInterceptorTabHelper.java

+// Copyright 2020 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.tab;
+
+/**
+ * Temporary wrapper to isolate downstream from the exact API surfaces used to get an
+ * AuthenticatorNavigationInterceptor instance from a Tab while those API surfaces are being
+ * refactored.
+ * TODO(blundell): Delete this once InterceptNavigationDelegateTabHelper has landed and
+ * InterceptNavigationDelegateImpl has been componentized in Chromium.
+ */
+public class AuthenticatorNavigationInterceptorTabHelper {
+    public static AuthenticatorNavigationInterceptor getInterceptorForTab(Tab tab) {
+        return InterceptNavigationDelegateImpl.get(tab).getAuthenticatorNavigationInterceptor();
+    }
+}