Reland: Add support for $i18n{} localized strings to ios/web.

ios/web/webui/web_ui_ios_data_source_impl.mm

Index: ios/web/webui/web_ui_ios_data_source_impl.mm
diff --git a/ios/web/webui/web_ui_ios_data_source_impl.mm b/ios/web/webui/web_ui_ios_data_source_impl.mm
index b51e26fe17e65c72c14e3d03d14593fb102c155c..189722fac972e2c9eebe4512379345fc78878a54 100644
--- a/ios/web/webui/web_ui_ios_data_source_impl.mm
+++ b/ios/web/webui/web_ui_ios_data_source_impl.mm
@@ -9,6 +9,7 @@
 #include "base/bind.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
 #import "ios/web/public/web_client.h"
 #include "ui/base/webui/jstemplate_builder.h"
 #include "ui/base/webui/web_ui_util.h"
@@ -65,6 +66,7 @@ WebUIIOSDataSourceImpl::WebUIIOSDataSourceImpl(const std::string& source_name)
       source_name_(source_name),
       default_resource_(-1),
       deny_xframe_options_(true),
+      load_time_data_defaults_added_(true),
       replace_existing_source_(true) {}
 
 WebUIIOSDataSourceImpl::~WebUIIOSDataSourceImpl() {}
@@ -72,16 +74,27 @@ WebUIIOSDataSourceImpl::~WebUIIOSDataSourceImpl() {}
 void WebUIIOSDataSourceImpl::AddString(const std::string& name,
                                        const base::string16& value) {
   localized_strings_.SetString(name, value);
+  replacements_[name] = base::UTF16ToUTF8(value);
 }
 
 void WebUIIOSDataSourceImpl::AddString(const std::string& name,
                                        const std::string& value) {
   localized_strings_.SetString(name, value);
+  replacements_[name] = value;
 }
 
 void WebUIIOSDataSourceImpl::AddLocalizedString(const std::string& name,
                                                 int ids) {
   localized_strings_.SetString(name, GetWebClient()->GetLocalizedString(ids));
+  replacements_[name] =
+      base::UTF16ToUTF8(GetWebClient()->GetLocalizedString(ids));
+}
+
+void WebUIIOSDataSourceImpl::AddLocalizedStrings(
+    const base::DictionaryValue& localized_strings) {
+  localized_strings_.MergeDictionary(&localized_strings);
+  ui::TemplateReplacementsFromDictionaryValue(localized_strings,
+                                              &replacements_);
 }
 
 void WebUIIOSDataSourceImpl::AddBoolean(const std::string& name, bool value) {
@@ -128,9 +141,22 @@ std::string WebUIIOSDataSourceImpl::GetMimeType(const std::string& path) const {
   return "text/html";
 }
 
+void WebUIIOSDataSourceImpl::EnsureLoadTimeDataDefaultsAdded() {
+  if (!load_time_data_defaults_added_)
+    return;
+
+  load_time_data_defaults_added_ = false;
+  base::DictionaryValue defaults;
+  webui::SetLoadTimeDataDefaults(web::GetWebClient()->GetApplicationLocale(),
+                                 &defaults);
+  AddLocalizedStrings(defaults);
+}
+
 void WebUIIOSDataSourceImpl::StartDataRequest(
     const std::string& path,
     const URLDataSourceIOS::GotDataCallback& callback) {
+  EnsureLoadTimeDataDefaultsAdded();
+
   if (!json_path_.empty() && path == json_path_) {
     SendLocalizedStringsAsJSON(callback);
     return;
@@ -142,24 +168,30 @@ void WebUIIOSDataSourceImpl::StartDataRequest(
   if (result != path_to_idr_map_.end())
     resource_id = result->second;
   DCHECK_NE(resource_id, -1);
-  SendFromResourceBundle(callback, resource_id);
+  SendFromResourceBundle(path, callback, resource_id);
 }
 
 void WebUIIOSDataSourceImpl::SendLocalizedStringsAsJSON(
     const URLDataSourceIOS::GotDataCallback& callback) {
   std::string template_data;
-  webui::SetLoadTimeDataDefaults(web::GetWebClient()->GetApplicationLocale(),
-                                 &localized_strings_);
-
   webui::AppendJsonJS(&localized_strings_, &template_data);
   callback.Run(base::RefCountedString::TakeString(&template_data));
 }
 
 void WebUIIOSDataSourceImpl::SendFromResourceBundle(
+    const std::string& path,
     const URLDataSourceIOS::GotDataCallback& callback,
     int idr) {
   scoped_refptr<base::RefCountedMemory> response(
       GetWebClient()->GetDataResourceBytes(idr));
+
+  if (response.get() && GetMimeType(path) == "text/html") {
+    std::string replaced = ui::ReplaceTemplateExpressions(
+        base::StringPiece(response->front_as<char>(), response->size()),
+        replacements_);
+    response = base::RefCountedString::TakeString(&replaced);
+  }
+
   callback.Run(response);
 }