Inline extensions .gypi files into GN build.

extensions/BUILD.gn

Index: extensions/BUILD.gn
diff --git a/extensions/BUILD.gn b/extensions/BUILD.gn
index d712e7815fad6f316094a88012ff64f9f389f007..2e95119cbfae8da8eafdeab135282d7965bef525 100644
--- a/extensions/BUILD.gn
+++ b/extensions/BUILD.gn
@@ -1,7 +1,6 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import("//extensions/extensions.gni")
 import("//testing/test.gni")
 import("//tools/grit/grit_rule.gni")
 import("//tools/grit/repack.gni")
@@ -60,9 +59,62 @@ grit("extensions_renderer_resources") {
 
 static_library("test_support") {
   testonly = true
-  sources = rebase_path(extensions_gypi_values.extensions_test_support_sources,
-                        ".",
-                        "//extensions")
+  sources = [
+    "browser/api/cast_channel/cast_test_util.cc",
+    "browser/api/cast_channel/cast_test_util.h",
+    "browser/api/dns/mock_host_resolver_creator.cc",
+    "browser/api/dns/mock_host_resolver_creator.h",
+    "browser/api/storage/settings_test_util.cc",
+    "browser/api/storage/settings_test_util.h",
+    "browser/api_test_utils.cc",
+    "browser/api_test_utils.h",
+    "browser/api_unittest.cc",
+    "browser/api_unittest.h",
+    "browser/app_window/test_app_window_contents.cc",
+    "browser/app_window/test_app_window_contents.h",
+    "browser/extension_error_test_util.cc",
+    "browser/extension_error_test_util.h",
+    "browser/extensions_test.cc",
+    "browser/extensions_test.h",
+    "browser/guest_view/mime_handler_view/test_mime_handler_view_guest.cc",
+    "browser/guest_view/mime_handler_view/test_mime_handler_view_guest.h",
+    "browser/mock_extension_system.cc",
+    "browser/mock_extension_system.h",
+    "browser/scoped_ignore_content_verifier_for_test.cc",
+    "browser/scoped_ignore_content_verifier_for_test.h",
+    "browser/test_extension_registry_observer.cc",
+    "browser/test_extension_registry_observer.h",
+    "browser/test_extensions_browser_client.cc",
+    "browser/test_extensions_browser_client.h",
+    "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/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",
+    "test/result_catcher.cc",
+    "test/result_catcher.h",
+    "test/test_content_utility_client.cc",
+    "test/test_content_utility_client.h",
+    "test/test_extensions_client.cc",
+    "test/test_extensions_client.h",
+    "test/test_permission_message_provider.cc",
+    "test/test_permission_message_provider.h",
+  ]
 
   # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]