text: const {ipcRenderer} = require('electron')
  const {runInThisContext} = require('vm')
  
  // Check whether pattern matches.
  // https://developer.chrome.com/extensions/match_patterns
  const matchesPattern = function (pattern) {
    if (pattern === '<all_urls>') return true
  
    const regexp = new RegExp('^' + pattern.replace(/\*/g, '.*') + '$')
    return location.href.match(regexp)
  }
  
  // Run the code with chrome API integrated.
  const runContentScript = function (extensionId, url, code) {
    const context = {}
    require('./chrome-api').injectTo(extensionId, false, context)
    const wrapper = `(function (chrome) {\n  ${code}\n  })`
    const compiledWrapper = runInThisContext(wrapper, {
      filename: url,
      lineOffset: 1,
      displayErrors: true
    })
    return compiledWrapper.call(this, context.chrome)
  }
  
  // Run injected scripts.
  // https://developer.chrome.com/extensions/content_scripts
  const injectContentScript = function (extensionId, script) {
    for (const match of script.matches) {
      if (!matchesPattern(match)) return
    }
  
    for (const {url, code} of script.js) {
      const fire = runContentScript.bind(window, extensionId, url, code)
      if (script.runAt === 'document_start') {
        process.once('document-start', fire)
      } else if (script.runAt === 'document_end') {
        process.once('document-end', fire)
      } else if (script.runAt === 'document_idle') {
        document.addEventListener('DOMContentLoaded', fire)
      }
    }
  }
  
  // Handle the request of chrome.tabs.executeJavaScript.
  ipcRenderer.on('CHROME_TABS_EXECUTESCRIPT', function (event, senderWebContentsId, requestId, extensionId, url, code) {
    const result = runContentScript.call(window, extensionId, url, code)
    ipcRenderer.sendToAll(senderWebContentsId, `CHROME_TABS_EXECUTESCRIPT_RESULT_${requestId}`, result)
  })
  
  // Read the renderer process preferences.
  const preferences = process.getRenderProcessPreferences()
  if (preferences) {
    for (const pref of preferences) {
      if (pref.contentScripts) {
        for (const script of pref.contentScripts) {
          injectContentScript(pref.extensionId, script)
        }
      }
    }
  }
  