[AI Chat] Preprocess html resources to include iOS specific scripts (#31480)

This change preprocesses the `ai_chat_ui.html` and `untrusted_conversation_frame.html` file so that if expression's are evaluated which allows us to add required scripts when using them in iOS

components/ai_chat/resources/BUILD.gn

@@ -4,6 +4,7 @@
 # You can obtain one at https://mozilla.org/MPL/2.0/.
 
 import("//brave/components/common/typescript.gni")
+import("//tools/grit/preprocess_if_expr.gni")
 
 transpile_web_ui("ai_chat_ui") {
   resource_name = "ai_chat_ui"
@@ -24,8 +25,21 @@ transpile_web_ui("ai_chat_ui") {
   ]
 }
 
+preprocess_if_expr("preprocess_html") {
+  visibility = [ ":resources_grit" ]
+  in_folder = "."
+  in_files = [
+    "page/ai_chat_ui.html",
+    "untrusted_conversation_frame/untrusted_conversation_frame.html",
+  ]
+  out_folder = "$target_gen_dir/preprocessed"
+}
+
 pack_web_resources("resources") {
   resource_name = "ai_chat_ui"
   output_dir = "$root_gen_dir/brave/components/ai_chat/resources"
-  deps = [ ":ai_chat_ui" ]
+  deps = [
+    ":ai_chat_ui",
+    ":preprocess_html",
+  ]
 }

components/ai_chat/resources/ai_chat_ui_resources.grdp

@@ -1,10 +1,12 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <grit-part>
-  <include name="IDR_AI_CHAT_UI_HTML" file="../ai_chat/resources/page/ai_chat_ui.html"
+  <include name="IDR_AI_CHAT_UI_HTML" file="${root_gen_dir}/brave/components/ai_chat/resources/preprocessed/page/ai_chat_ui.html"
+    use_base_dir="false"
     type="BINDATA" />
   <include name="IDR_AI_CHAT_UI_CSS" file="../ai_chat/resources/page/styles.css" type="BINDATA" />
   <include name="IDR_AI_CHAT_UNTRUSTED_CONVERSATION_UI_HTML"
-    file="../ai_chat/resources/untrusted_conversation_frame/untrusted_conversation_frame.html"
+    file="${root_gen_dir}/brave/components/ai_chat/resources/preprocessed/untrusted_conversation_frame/untrusted_conversation_frame.html"
+    use_base_dir="false"
     type="BINDATA" />
   <include name="IDR_AI_CHAT_UI_MANIFEST" file="../ai_chat/resources/page/manifest.webmanifest" type="BINDATA" />
   <include name="IDR_AI_CHAT_UI_PWA_ICON" file="../ai_chat/resources/page/pwa_icon.svg" type="BINDATA" />

components/ai_chat/resources/page/ai_chat_ui.html

@@ -14,6 +14,10 @@
     <script src="//resources/js/load_time_data_deprecated.js"></script>
     <script src="/strings.js"></script>
     <script src="chat_ui.bundle.js" type="module"></script>
+<if expr="is_ios">
+    <script src="//resources/js/ios/web_ui.js"></script>
+    <script src="//resources/js/ios/mojo_api.js"></script>
+</if>
     <link rel="icon" href="//resources/brave-icons/social-leo-favicon-fullheight-color.svg">
     <link rel="manifest" href="manifest.webmanifest">
     <style>

components/ai_chat/resources/untrusted_conversation_frame/untrusted_conversation_frame.html

@@ -13,6 +13,10 @@
     <script src="//resources/js/load_time_data_deprecated.js"></script>
     <script src="/strings.js"></script>
     <script src="untrusted_conversation_frame.bundle.js" type="module"></script>
+<if expr="is_ios">
+    <script src="//resources/js/ios/web_ui.js"></script>
+    <script src="//resources/js/ios/mojo_api.js"></script>
+</if>
     <style>
       body {
         /* This page is designed to be embedded in an opaque iframe */

components/resources/BUILD.gn

@@ -25,6 +25,7 @@ brave_grit("static_resources") {
   ]
   deps = [
     ":strings",
+    "//brave/components/ai_chat/resources",
     "//brave/components/brave_rewards/resources",
     "//brave/components/brave_shields/resources:bundle_js",
     "//brave/components/decentralized_dns/content/resources:bundle_js",