[iOS][WidgetKit] Add extension skeleton and flag

bug: 1138710
Change-Id: I9c1c787837d6c64e7ef88c66bf9070bb7d073547
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2477236Reviewed-by: Sergio Collazos <sczs@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Commit-Queue: Javier Ernesto Flores Robles <javierrobles@chromium.org>
Cr-Commit-Position: refs/heads/master@{#819816}

ios/build/chrome_build.gni

@@ -11,6 +11,9 @@ declare_args() {
   ios_enable_content_widget_extension = true
   ios_enable_search_widget_extension = true
 
+  # Enable iOS 14, WidgetKit extension.
+  ios_enable_widget_kit_extension = false
+
   # Enable share extension.
   ios_enable_share_extension = true
 

ios/chrome/app/BUILD.gn

@@ -384,6 +384,9 @@ ios_app_bundle("chrome") {
     if (ios_enable_credential_provider_extension) {
       deps += [ ":credential_provider_extension_bundle" ]
     }
+    if (ios_enable_widget_kit_extension) {
+      deps += [ ":widget_kit_extension_bundle" ]
+    }
   }
 
   extra_substitutions = [
@@ -451,4 +454,14 @@ if (current_toolchain == default_toolchain) {
       outputs = [ "{{bundle_contents_dir}}/PlugIns/{{source_file_part}}" ]
     }
   }
+
+  if (ios_enable_widget_kit_extension) {
+    bundle_data("widget_kit_extension_bundle") {
+      _widget_extension_target = "//ios/chrome/widget_kit_extension"
+      public_deps = [ _widget_extension_target ]
+      sources = [ get_label_info(_widget_extension_target, "root_out_dir") +
+                  "/widget_kit_extension.appex" ]
+      outputs = [ "{{bundle_contents_dir}}/PlugIns/{{source_file_part}}" ]
+    }
+  }
 }

ios/chrome/widget_kit_extension/BUILD.gn

+# Copyright 2020 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/apple/tweak_info_plist.gni")
+import("//build/config/ios/rules.gni")
+import("//build/config/locales.gni")
+import("//build/config/mac/base_rules.gni")
+import("//ios/build/chrome_build.gni")
+import("//ios/build/config.gni")
+import("//ios/chrome/extension_repack.gni")
+import("//ios/chrome/tools/strings/generate_localizable_strings.gni")
+import("//ios/public/provider/chrome/browser/build_config.gni")
+
+tweak_info_plist("tweak_info_plist") {
+  info_plist = "Info.plist"
+}
+
+compile_entitlements("entitlements") {
+  substitutions = [
+    "IOS_BUNDLE_ID_PREFIX=$ios_app_bundle_id_prefix",
+    "CHROMIUM_BUNDLE_ID=$chromium_bundle_id",
+  ]
+  output_name = "$target_gen_dir/widget_kit_extension.appex.entitlements"
+  entitlements_templates =
+      [ "entitlements/external/widget_kit_extension.appex.entitlements" ]
+  if (ios_chrome_cpe_entitlements_additions != []) {
+    entitlements_templates += ios_chrome_cpe_entitlements_additions
+  }
+}
+
+ios_appex_bundle("widget_kit_extension") {
+  sources = []
+
+  configs += [ "//build/config/compiler:enable_arc" ]
+
+  frameworks = [
+    "WidgetKit.framework",
+    "Foundation.framework",
+    "SwiftUI.framework",
+  ]
+  entitlements_target = ":entitlements"
+  info_plist_target = ":tweak_info_plist"
+  xcode_product_bundle_id = "$chromium_bundle_id.WidgetKitExtension"
+
+  extra_substitutions = [ "PRODUCT_BUNDLE_IDENTIFIER=$ios_app_bundle_id_prefix.$xcode_product_bundle_id" ]
+}

ios/chrome/widget_kit_extension/Info.plist

+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDevelopmentRegion</key>
+	<string>en</string>
+	<key>CFBundleDisplayName</key>
+	<string>widget-extension</string>
+	<key>CFBundleExecutable</key>
+	<string>${EXECUTABLE_NAME}</string>
+	<key>CFBundleIdentifier</key>
+	<string>${PRODUCT_BUNDLE_IDENTIFIER}</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleName</key>
+	<string>${PRODUCT_NAME}</string>
+	<key>CFBundlePackageType</key>
+	<string>XPC!</string>
+	<key>CFBundleShortVersionString</key>
+	<string>1.0</string>
+	<key>CFBundleVersion</key>
+	<string>1</string>
+	<key>NSExtension</key>
+	<dict>
+		<key>NSExtensionPointIdentifier</key>
+		<string>com.apple.widgetkit-extension</string>
+	</dict>
+	<key>UIRequiredDeviceCapabilities</key>
+	<array>
+		<string>arm64</string>
+	</array>
+</dict>
+</plist>

ios/chrome/widget_kit_extension/entitlements/external/widget_kit_extension.appex.entitlements

+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>application-identifier</key>
+	<string>$(AppIdentifierPrefix)$(CFBundleIdentifier)</string>
+	<key>com.apple.security.application-groups</key>
+	<array>
+		<string>group.${IOS_BUNDLE_ID_PREFIX}.chrome</string>
+		<string>group.${IOS_BUNDLE_ID_PREFIX}.common</string>
+	</array>
+</dict>
+</plist>