Extracted MockManifestPermission to its own file

extensions/BUILD.gn

 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//extensions/features/features.gni")
 import("//testing/test.gni")
 import("//tools/grit/grit_rule.gni")
 import("//tools/grit/repack.gni")
 
 assert(enable_extensions)
 
@@ skipping 82 matching lines @@
     "browser/test_image_loader.cc",
     "browser/test_image_loader.h",
     "browser/test_management_policy.cc",
     "browser/test_management_policy.h",
     "browser/test_runtime_api_delegate.cc",
     "browser/test_runtime_api_delegate.h",
     "common/extension_builder.cc",
     "common/extension_builder.h",
     "common/manifest_test.cc",
     "common/manifest_test.h",
+    "common/permissions/mock_manifest_permission.cc",
+    "common/permissions/mock_manifest_permission.h",
     "common/permissions/permission_message_test_util.cc",
     "common/permissions/permission_message_test_util.h",
     "common/test_util.cc",
     "common/test_util.h",
     "renderer/test_extensions_renderer_client.cc",
     "renderer/test_extensions_renderer_client.h",
     "test/background_page_watcher.cc",
     "test/background_page_watcher.h",
     "test/extension_test_message_listener.cc",
     "test/extension_test_message_listener.h",
@@ skipping 240 matching lines @@
     "//testing/gtest",
     "//third_party/hunspell",
     "//third_party/icu",
     "//third_party/libpng",
     "//third_party/zlib",
     "//ui/base:test_support",
     "//ui/resources:ui_test_pak",
     "//ui/web_dialogs:test_support",
   ]
 }