Add gn implementation of //ios/web/shell:ios_web_shell.

ios/web/shell/BUILD.gn

Index: ios/web/shell/BUILD.gn
diff --git a/ios/web/shell/BUILD.gn b/ios/web/shell/BUILD.gn
new file mode 100644
index 0000000000000000000000000000000000000000..3d9e9676eae9d2c263b19c6475719bc619c5400c
--- /dev/null
+++ b/ios/web/shell/BUILD.gn
@@ -0,0 +1,70 @@
+# Copyright 2015 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/rules.gni")
+
+ios_app("ios_web_shell") {
+  info_plist = "Info.plist"
+  app_name = "ios_web_shell"
+  entitlements_path = ""
+  code_signing_identity = ""
+
+  sources = [
+    "app_delegate.h",
+    "app_delegate.mm",
+    "shell_browser_state.h",
+    "shell_browser_state.mm",
+    "shell_main_delegate.h",
+    "shell_main_delegate.mm",
+    "shell_network_delegate.cc",
+    "shell_network_delegate.h",
+    "shell_url_request_context_getter.cc",
+    "shell_url_request_context_getter.h",
+    "shell_web_client.h",
+    "shell_web_client.mm",
+    "shell_web_main_parts.h",
+    "shell_web_main_parts.mm",
+    "view_controller.h",
+    "view_controller.mm",
+    "web_exe_main.mm",
+  ]
+
+  deps = [
+    "//base",
+    "//ios/web",
+    "//ios/web/public/app",
+    "//net",
+    "//net:extras",
+    "//ui/base",
+
+    # All shared libraries must have the sanitizer deps to properly link in
+    # asan mode (this target will be empty in other cases).
+    "//build/config/sanitizers:deps",
+  ]
+
+  ldflags = [
+    "-Xlinker",
+    "-objc_abi_version",
+    "-Xlinker",
+    "2",
+  ]
+
+  libs = [
+    "CoreGraphics.framework",
+    "CoreFoundation.framework",
+    "Foundation.framework",
+    "UIKit.framework",
+  ]
+
+  # TODO(crbug.com/546283): once gn supports bundle resources, add support for
+  # the following gyp code:
+  #
+  # 'mac_bundle_resources': [
+  #   'shell/Default.png',
+  #   'shell/MainView.xib',
+  #   'shell/textfield_background@2x.png',
+  #   'shell/toolbar_back@2x.png',
+  #   'shell/toolbar_forward@2x.png',
+  # ],
+}