Implement chrome.extension.connectExternal and fix various API inconsistencies.

chrome/test/data/extensions/api_test/connect_external/connect.html

Index: chrome/test/data/extensions/api_test/connect_external/connect.html
diff --git a/chrome/test/data/extensions/api_test/connect_external/connect.html b/chrome/test/data/extensions/api_test/connect_external/connect.html
new file mode 100644
index 0000000000000000000000000000000000000000..cc9def80d9682083952e52208f22ff9a48f21d5a
--- /dev/null
+++ b/chrome/test/data/extensions/api_test/connect_external/connect.html
@@ -0,0 +1,13 @@
+<script>
+var testId = "bjafgdebaacbbbecmhlhpofkepfkgcpa";
+
+function testConnectExternal() {
+  var port = chrome.extension.connect(testId, {name: "extern"});
+  port.postMessage({testConnectExternal: true});
+  port.onMessage.addListener(function(msg) {
+    var success = msg.success && msg.senderId == location.host;
+    window.domAutomationController.send(success);
+    port.disconnect();
+  });
+}
+</script>