build: allow use of BUILDFLAG directives from within JS code (#20328)

build/webpack/webpack.config.base.js

@@ -20,6 +20,54 @@ class AccessDependenciesPlugin {
   }
 }
 
+const defines = {
+  BUILDFLAG: ' '
+}
+
+const buildFlagsPrefix = '--buildflags='
+const buildFlagArg = process.argv.find(arg => arg.startsWith(buildFlagsPrefix));
+
+if (buildFlagArg) {
+  const buildFlagPath = buildFlagArg.substr(buildFlagsPrefix.length)
+
+  const flagFile = fs.readFileSync(buildFlagPath, 'utf8')
+  for (const line of flagFile.split(/(\r\n|\r|\n)/g)) {
+    const flagMatch = line.match(/#define BUILDFLAG_INTERNAL_(.+?)\(\) \(([01])\)/)
+    if (flagMatch) {
+      const flagName = flagMatch[1];
+      const flagValue = flagMatch[2];
+      defines[flagName] = JSON.stringify(Boolean(parseInt(flagValue, 10)));
+    }
+  }
+}
+
+const ignoredModules = []
+
+if (defines['ENABLE_DESKTOP_CAPTURER'] === 'false') {
+  ignoredModules.push(
+    '@electron/internal/browser/desktop-capturer',
+    '@electron/internal/renderer/api/desktop-capturer'
+  )
+}
+
+if (defines['ENABLE_REMOTE_MODULE'] === 'false') {
+  ignoredModules.push(
+    '@electron/internal/browser/remote/server',
+    '@electron/internal/renderer/api/remote'
+  )
+}
+
+if (defines['ENABLE_VIEWS_API'] === 'false') {
+  ignoredModules.push(
+    '@electron/internal/browser/api/views/image-view.js'
+  )
+}
+
+const alias = {}
+for (const ignoredModule of ignoredModules) {
+  alias[ignoredModule] = path.resolve(electronRoot, 'lib/common/dummy.js')
+}
+
 module.exports = ({
   alwaysHasNode,
   loadElectronFromAlternateTarget,
@@ -41,6 +89,7 @@ module.exports = ({
     },
     resolve: {
       alias: {
+        ...alias,
         '@electron/internal': path.resolve(electronRoot, 'lib'),
         'electron': path.resolve(electronRoot, 'lib', loadElectronFromAlternateTarget || target, 'api', 'exports', 'electron.ts'),
         // Force timers to resolve to our dependency that doens't use window.postMessage
@@ -78,6 +127,7 @@ module.exports = ({
       new webpack.ProvidePlugin({
         Promise: ['@electron/internal/common/webpack-globals-provider', 'Promise'],
       }),
+      new webpack.DefinePlugin(defines),
     ]
   })
 }