chore: convert extension apis to TypeScript (#18688)

Converts extensions-related files to TS

lib/renderer/extensions/i18n.ts

@@ -0,0 +1,60 @@
+// Implementation of chrome.i18n.getMessage
+// https://developer.chrome.com/extensions/i18n#method-getMessage
+//
+// Does not implement predefined messages:
+// https://developer.chrome.com/extensions/i18n#overview-predefined
+
+import * as ipcRendererUtils from '@electron/internal/renderer/ipc-renderer-internal-utils'
+
+interface Placeholder {
+  content: string;
+  example?: string;
+}
+
+const getMessages = (extensionId: number) => {
+  try {
+    const data = ipcRendererUtils.invokeSync<string>('CHROME_GET_MESSAGES', extensionId)
+    return JSON.parse(data) || {}
+  } catch {
+    return {}
+  }
+}
+
+const replaceNumberedSubstitutions = (message: string, substitutions: string[]) => {
+  return message.replace(/\$(\d+)/, (_, number) => {
+    const index = parseInt(number, 10) - 1
+    return substitutions[index] || ''
+  })
+}
+
+const replacePlaceholders = (message: string, placeholders: Record<string, Placeholder>, substitutions: string[] | string) => {
+  if (typeof substitutions === 'string') substitutions = [substitutions]
+  if (!Array.isArray(substitutions)) substitutions = []
+
+  if (placeholders) {
+    Object.keys(placeholders).forEach((name: string) => {
+      let { content } = placeholders[name]
+      const substitutionsArray = Array.isArray(substitutions) ? substitutions : []
+      content = replaceNumberedSubstitutions(content, substitutionsArray)
+      message = message.replace(new RegExp(`\\$${name}\\$`, 'gi'), content)
+    })
+  }
+
+  return replaceNumberedSubstitutions(message, substitutions)
+}
+
+const getMessage = (extensionId: number, messageName: string, substitutions: string[]) => {
+  const messages = getMessages(extensionId)
+  if (messages.hasOwnProperty(messageName)) {
+    const { message, placeholders } = messages[messageName]
+    return replacePlaceholders(message, placeholders, substitutions)
+  }
+}
+
+exports.setup = (extensionId: number) => {
+  return {
+    getMessage (messageName: string, substitutions: string[]) {
+      return getMessage(extensionId, messageName, substitutions)
+    }
+  }
+}