Implement initial chrome.browserAction.openPopup API.

chrome/renderer/resources/extensions/browser_action_custom_bindings.js

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Custom binding for the browserAction API.
 
 var binding = require('binding').Binding.create('browserAction');
 
 var setIcon = require('setIcon').setIcon;
+var getExtensionViews = requireNative('extension').GetExtensionViews;
 
 binding.registerCustomHook(function(bindingsAPI) {
   var apiFunctions = bindingsAPI.apiFunctions;
 
   apiFunctions.setHandleRequest('setIcon', function(details, callback) {
     setIcon(details, callback, this.name, this.definition.parameters,
         'browser action');
   });
+
+  apiFunctions.setCustomCallback('openPopup',
+                                 function(name, request, response) {
+    if (chrome.runtime.lastError)
+      throw new Error(chrome.runtime.lastError.message);

[not at google - send to devlin, 2013/10/23 23:18:42]

don't throw an error here. chrome.runtime.lastError should just be set for the
callback. the code for this should look something like

if (!request.callback)
  return;

if (chrome.runtime.lastError) {
  request.callback();
  return;
}

[justinlin, 2013/10/24 00:01:38]

Ah thanks. https://codereview.chromium.org/32283005/. I thought API's can throw
an exception as well on error, but I think that's only for before the call when
things like input parameters are the wrong type. 

+
+    if (!request.callback)
+      return;
+
+    var views = getExtensionViews(-1, 'POPUP');
+    request.callback(views.length > 0 ? views[0] : null);
+    request.callback = null;
+  });
 });
 
 exports.binding = binding.generate();