Add machinery to show touch editing context menus in OOPIFs.

third_party/WebKit/Source/core/frame/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("//third_party/WebKit/Source/core/core.gni")
 
 blink_core_sources("frame") {
   sources = [
     "BarProp.cpp",
     "BarProp.h",
     "BrowserControls.cpp",
     "BrowserControls.h",
     "ContentSettingsClient.cpp",
     "ContentSettingsClient.h",
+    "ContextMenuAllowedScope.cpp",
+    "ContextMenuAllowedScope.h",
     "DOMTimer.cpp",
     "DOMTimer.h",
     "DOMTimerCoordinator.cpp",
     "DOMTimerCoordinator.h",
     "DOMVisualViewport.cpp",
     "DOMVisualViewport.h",
     "DOMWindow.cpp",
     "DOMWindow.h",
     "DOMWindowBase64.cpp",
     "DOMWindowBase64.h",
@@ skipping 109 matching lines @@
     "csp/MediaListDirective.h",
     "csp/SourceListDirective.cpp",
     "csp/SourceListDirective.h",
   ]
 
   configs += [
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     "//build/config/compiler:no_size_t_to_int_warning",
   ]
 }