Fix context menu for sandbox devtools (#11933)

lib/sandboxed_renderer/init.js

@@ -32,8 +32,6 @@ const preloadModules = new Map([
   ['timers', require('timers')]
 ])
 
-const preloadSrc = fs.readFileSync(preloadPath).toString()
-
 // Pass different process object to the preload script(which should not have
 // access to things like `process.atomBinding`).
 const preloadProcess = new events.EventEmitter()
@@ -55,6 +53,11 @@ function preloadRequire (module) {
   throw new Error('module not found')
 }
 
+if (window.location.protocol === 'chrome-devtools:') {
+  // Override some inspector APIs.
+  require('../renderer/inspector')
+}
+
 // Wrap the script into a function executed in global scope. It won't have
 // access to the current scope, so we'll expose a few objects as arguments:
 //
@@ -74,13 +77,16 @@ function preloadRequire (module) {
 // and any `require('electron')` calls in `preload.js` will work as expected
 // since browserify won't try to include `electron` in the bundle, falling back
 // to the `preloadRequire` function above.
-const preloadWrapperSrc = `(function(require, process, Buffer, global, setImmediate) {
-${preloadSrc}
-})`
+if (preloadPath) {
+  const preloadSrc = fs.readFileSync(preloadPath).toString()
+  const preloadWrapperSrc = `(function(require, process, Buffer, global, setImmediate) {
+  ${preloadSrc}
+  })`
 
-// eval in window scope:
-// http://www.ecma-international.org/ecma-262/5.1/#sec-10.4.2
-const geval = eval
-const preloadFn = geval(preloadWrapperSrc)
-const {setImmediate} = require('timers')
-preloadFn(preloadRequire, preloadProcess, Buffer, global, setImmediate)
+  // eval in window scope:
+  // http://www.ecma-international.org/ecma-262/5.1/#sec-10.4.2
+  const geval = eval
+  const preloadFn = geval(preloadWrapperSrc)
+  const {setImmediate} = require('timers')
+  preloadFn(preloadRequire, preloadProcess, Buffer, global, setImmediate)
+}