Remove AppHooks' ExternalAuthUtils

* Now that ExternalAuthUtils is provided as a singleton instance,
  remove AppHooks' instance and related methods.
* This is patch 5/5 for providing ExternalAuthUtils as a singleton
  instead of from AppHooks.

Change-Id: I4278d4a6663a1d8a48314ffa2b812df722e93e12
Bug: 1154371
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2587240
Commit-Queue: Nick Burris <nburris@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837725}

chrome/android/java/src/org/chromium/chrome/browser/AppHooks.java

@@ -48,7 +48,6 @@ import org.chromium.chrome.browser.xsurface.ProcessScopeDependencyProvider;
 import org.chromium.chrome.modules.image_editor.ImageEditorModuleProvider;
 import org.chromium.components.browser_ui.widget.FeatureHighlightProvider;
 import org.chromium.components.external_intents.AuthenticatorNavigationInterceptor;
-import org.chromium.components.externalauth.ExternalAuthUtils;
 import org.chromium.components.policy.AppRestrictionsProvider;
 import org.chromium.components.policy.CombinedPolicyProvider;
 import org.chromium.components.signin.AccountManagerDelegate;
@@ -65,9 +64,6 @@ import java.util.List;
 public abstract class AppHooks {
     private static AppHooksImpl sInstance;
 
-    @Nullable
-    private ExternalAuthUtils mExternalAuthUtils;
-
     /**
      * Sets a mocked instance for testing.
      */
@@ -138,24 +134,6 @@ public abstract class AppHooks {
         return new SurveyController();
     }
 
-    /**
-     * @return An instance of ExternalAuthUtils to be installed as a singleton.
-     */
-    protected ExternalAuthUtils createExternalAuthUtils() {
-        return new ExternalAuthUtils();
-    }
-
-    /**
-     * @return The singleton instance of ExternalAuthUtils.
-     */
-    public ExternalAuthUtils getExternalAuthUtils() {
-        if (mExternalAuthUtils == null) {
-            mExternalAuthUtils = createExternalAuthUtils();
-        }
-
-        return mExternalAuthUtils;
-    }
-
     /**
      * @return An instance of {@link FeedbackReporter} to report feedback.
      */