Remove unused feedback class in dom distiller component

chrome/android/java_sources.gni

 # Copyright 2016 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.
 
 chrome_java_sources = [
   "java/src/com/google/android/apps/chrome/appwidget/bookmarks/BookmarkThumbnailWidgetProvider.java",
   "java/src/org/chromium/chrome/browser/ActivityTabTaskDescriptionHelper.java",
   "java/src/org/chromium/chrome/browser/ActivityTaskDescriptionIconGenerator.java",
   "java/src/org/chromium/chrome/browser/AfterStartupTaskUtils.java",
   "java/src/org/chromium/chrome/browser/ApplicationInitialization.java",
@@ skipping 109 matching lines @@
   "java/src/org/chromium/chrome/browser/bookmarks/BookmarkUIObserver.java",
   "java/src/org/chromium/chrome/browser/bookmarks/BookmarkUIState.java",
   "java/src/org/chromium/chrome/browser/bookmarks/BookmarkUndoController.java",
   "java/src/org/chromium/chrome/browser/bookmarks/BookmarkUtils.java",
   "java/src/org/chromium/chrome/browser/bookmarkswidget/BookmarkWidgetProvider.java",
   "java/src/org/chromium/chrome/browser/bookmarkswidget/BookmarkWidgetProxy.java",
   "java/src/org/chromium/chrome/browser/bookmarkswidget/BookmarkWidgetService.java",
   "java/src/org/chromium/chrome/browser/browsing_data/UrlFilters.java",
   "java/src/org/chromium/chrome/browser/childaccounts/ChildAccountFeedbackReporter.java",
   "java/src/org/chromium/chrome/browser/childaccounts/ChildAccountService.java",
-  "java/src/org/chromium/chrome/browser/childaccounts/ExternalFeedbackReporter.java",
   "java/src/org/chromium/chrome/browser/compositor/CompositorSurfaceManager.java",
   "java/src/org/chromium/chrome/browser/compositor/CompositorView.java",
   "java/src/org/chromium/chrome/browser/compositor/CompositorViewHolder.java",
   "java/src/org/chromium/chrome/browser/compositor/Invalidator.java",
   "java/src/org/chromium/chrome/browser/compositor/LayerTitleCache.java",
   "java/src/org/chromium/chrome/browser/compositor/TitleCache.java",
   "java/src/org/chromium/chrome/browser/compositor/bottombar/OverlayContentDelegate.java",
   "java/src/org/chromium/chrome/browser/compositor/bottombar/OverlayContentProgressObserver.java",
   "java/src/org/chromium/chrome/browser/compositor/bottombar/OverlayPanel.java",
   "java/src/org/chromium/chrome/browser/compositor/bottombar/OverlayPanelAnimation.java",
@@ skipping 1518 matching lines @@
   "sync_shell/javatests/src/org/chromium/chrome/browser/sync/SyncTestBase.java",
   "sync_shell/javatests/src/org/chromium/chrome/browser/sync/TypedUrlsTest.java",
   "sync_shell/javatests/src/org/chromium/chrome/browser/sync/ui/PassphraseTypeDialogFragmentTest.java",
 ]
 
 # Only used for testing, should not be shipped to end users.
 if (!is_official_build) {
   chrome_java_sources += [ "java/src/org/chromium/chrome/browser/offlinepages/evaluation/OfflinePageEvaluationBridge.java" ]
   chrome_test_java_sources += [ "javatests/src/org/chromium/chrome/browser/offlinepages/OfflinePageSavePageLaterEvaluationTest.java" ]
 }