Implement CWVWebView.scrollView.

ios/web_view/BUILD.gn

 # 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.
 
 import("//build/config/ios/ios_sdk.gni")
 import("//build/config/ios/rules.gni")
 import("//tools/grit/repack.gni")
 
 config("config") {
   defines = [ "CWV_IMPLEMENTATION" ]
   libs = [
     "CoreGraphics.framework",
     "Foundation.framework",
     "MobileCoreServices.framework",
     "UIKit.framework",
   ]
 }
 
 # These variables are used to share framework sources with both ChromeWebView
 # and CrNetChromeWebView frameworks.
 ios_web_view_public_headers = [
   "public/ChromeWebView.h",
   "public/cwv_export.h",
   "public/cwv_html_element.h",
   "public/cwv_navigation_action.h",
   "public/cwv_navigation_delegate.h",
+  "public/cwv_scroll_view.h",
+  "public/cwv_scroll_view_delegate.h",
   "public/cwv_translate_delegate.h",
   "public/cwv_translate_manager.h",
   "public/cwv_ui_delegate.h",
   "public/cwv_user_content_controller.h",
   "public/cwv_user_script.h",
   "public/cwv_web_view.h",
   "public/cwv_web_view_configuration.h",
 ]
 
 ios_web_view_sources = [
   "internal/cwv_html_element.mm",
   "internal/cwv_html_element_internal.h",
   "internal/cwv_navigation_action.mm",
   "internal/cwv_navigation_action_internal.h",
+  "internal/cwv_scroll_view.mm",
+  "internal/cwv_scroll_view_internal.h",
   "internal/cwv_user_content_controller.mm",
   "internal/cwv_user_content_controller_internal.h",
   "internal/cwv_user_script.mm",
   "internal/cwv_web_view.mm",
   "internal/cwv_web_view_configuration.mm",
   "internal/cwv_web_view_configuration_internal.h",
   "internal/pref_names.cc",
   "internal/pref_names.h",
   "internal/translate/cwv_translate_manager_impl.h",
   "internal/translate/cwv_translate_manager_impl.mm",
@@ skipping 130 matching lines @@
   ]
   args = [
     "license_file",
     rebase_path(_license_path, root_build_dir),
     "--gn-target",
     "//ios/web_view",
     "--gn-out-dir",
     ".",
   ]
 }