Remember loaded extensions.

atom/browser/api/lib/browser-window.coffee

@@ -36,7 +36,7 @@ BrowserWindow::openDevTools = ->
   @devToolsWebContents.once 'destroyed', => @devToolsWebContents = null
 
   # Emit devtools events.
-  @emit 'dev-tools-opened'
+  @devToolsWebContents.once 'did-finish-load', => @emit 'dev-tools-opened'
   @devToolsWebContents.once 'destroyed', => @emit 'dev-tools-closed'
 
 BrowserWindow::toggleDevTools = ->

atom/browser/lib/chrome-extension.coffee

@@ -15,22 +15,12 @@ getHostForPath = (path) ->
 getPathForHost = (host) ->
   hostPathMap[host]
 
-app.once 'ready', ->
-  protocol = require 'protocol'
-  BrowserWindow = require 'browser-window'
-
-  protocol.registerProtocol 'chrome-extension', (request) ->
-    parsed = url.parse request.url
-    return unless parsed.hostname and parsed.path?
-
-    return unless /extension-\d+/.test parsed.hostname
-
-    directory = getPathForHost parsed.hostname
-    return new protocol.RequestFileJob(path.join(directory, parsed.path))
-
-  BrowserWindow::loadDevToolsExtension = (srcDirectory) ->
-    manifest = JSON.parse fs.readFileSync(path.join(srcDirectory, 'manifest.json'))
+# Cache extensionInfo.
+extensionInfoMap = {}
 
+getExtensionInfoFromPath = (srcDirectory) ->
+  manifest = JSON.parse fs.readFileSync(path.join(srcDirectory, 'manifest.json'))
+  unless extensionInfoMap[manifest.name]?
     # We can not use 'file://' directly because all resources in the extension
     # will be treated as relative to the root in Chrome.
     page = url.format
@@ -38,6 +28,61 @@ app.once 'ready', ->
       slashes: true
       hostname: getHostForPath srcDirectory
       pathname: manifest.devtools_page
+    extensionInfoMap[manifest.name] =
+      startPage: page
+      name: manifest.name
+      srcDirectory: srcDirectory
+  extensionInfoMap[manifest.name]
 
-    extensionInfo = startPage: page, name: manifest.name
-    @devToolsWebContents?.executeJavaScript "WebInspector.addExtensions([#{JSON.stringify(extensionInfo)}]);"
+# Load persistented extensions.
+loadedExtensionsPath = path.join app.getDataPath(), 'DevTools Extensions'
+
+try
+  loadedExtensions = JSON.parse fs.readFileSync(loadedExtensionsPath)
+  loadedExtensions = [] unless Array.isArray loadedExtensions
+  # Preheat the extensionInfo cache.
+  getExtensionInfoFromPath srcDirectory for srcDirectory in loadedExtensions
+catch e
+
+# Persistent loaded extensions.
+app.on 'will-quit', ->
+  try
+    loadedExtensions = Object.keys(extensionInfoMap).map (key) -> extensionInfoMap[key].srcDirectory
+    try
+      fs.mkdirSync path.dirname(loadedExtensionsPath)
+    catch e
+    fs.writeFileSync loadedExtensionsPath, JSON.stringify(loadedExtensions)
+  catch e
+
+# We can not use protocol or BrowserWindow until app is ready.
+app.once 'ready', ->
+  protocol = require 'protocol'
+  BrowserWindow = require 'browser-window'
+
+  # The chrome-extension: can map a extension URL request to real file path.
+  protocol.registerProtocol 'chrome-extension', (request) ->
+    parsed = url.parse request.url
+    return unless parsed.hostname and parsed.path?
+    return unless /extension-\d+/.test parsed.hostname
+
+    directory = getPathForHost parsed.hostname
+    return unless directory?
+    return new protocol.RequestFileJob(path.join(directory, parsed.path))
+
+  BrowserWindow::_loadDevToolsExtensions = (extensionInfoArray) ->
+    @devToolsWebContents?.executeJavaScript "WebInspector.addExtensions(#{JSON.stringify(extensionInfoArray)});"
+
+  BrowserWindow.addDevToolsExtension = (srcDirectory) ->
+    extensionInfo = getExtensionInfoFromPath srcDirectory
+    window._loadDevToolsExtensions [extensionInfo] for window in BrowserWindow.getAllWindows()
+    extensionInfo.name
+
+  BrowserWindow.removeDevToolsExtension = (name) ->
+    delete extensionInfoMap[name]
+
+  # Load persistented extensions when devtools is opened.
+  init = BrowserWindow::_init
+  BrowserWindow::_init = ->
+    init.call this
+    @on 'dev-tools-opened', ->
+      @_loadDevToolsExtensions Object.keys(extensionInfoMap).map (key) -> extensionInfoMap[key]

atom/browser/lib/init.coffee

@@ -52,9 +52,6 @@ setImmediate ->
       detail: message
       buttons: ['OK']
 
-  # Load the chrome extension support.
-  require './chrome-extension.js'
-
   # Load the RPC server.
   require './rpc-server.js'
 
@@ -80,5 +77,8 @@ setImmediate ->
   else if packageJson.name?
     app.setName packageJson.name
 
+  # Load the chrome extension support.
+  require './chrome-extension.js'
+
   # Finally load app's main.js and transfer control to C++.
   module._load path.join(packagePath, packageJson.main), module, true