bluetoothPrivate: Add disconnectAll function

chrome/test/data/extensions/api_test/bluetooth_private/disconnect/test.js

+// Copyright 2014 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.
+
+var deviceAddress = '11:12:13:14:15:16';
+var errorNotConnected = 'Device is not connected';
+var errorDisconnectFailed = 'Failed to disconnect device';

[Jeffrey Yasskin, 2014/12/20 00:53:48]

This message has been really annoying when debugging uses of the bluetooth API.
Can you report anything more precise?

And yes, you can. BluetoothDeviceChromeOS::OnDisconnectError() gets an error
description and then THROWS IT AWAY. That's really not an acceptable way to
treat our developers.

[armansito, 2014/12/20 01:24:28]

The only error that BlueZ returns is 'org.bluez.Error.NotConnected' (see
http://git.kernel.org/cgit/bluetooth/bluez.git/tree/doc/device-api.txt#n29).
We're already returning errorNotConnected here at the API level by doing the
check ourselves.

[Jeffrey Yasskin, 2014/12/20 01:29:58]

If this error case is impossible, you should probably DCHECK that it doesn't
happen instead of writing code to send an incorrect message to developers if it
does happen. I suspect there's a race condition during the several cross-process
hops in which it does happen, though.

[armansito, 2014/12/20 01:43:38]

No it's not impossible. I'm not sure I'm following you here. In what case are we
returning an incorrect error message from this function?

+
+var btp = chrome.bluetoothPrivate;
+
+function testDisconnect() {
+  btp.disconnect(deviceAddress, function() {
+    assertFailure(errorNotConnected);
+    btp.disconnect(deviceAddress, function() {
+      assertFailure(errorDisconnectFailed);
+      btp.disconnect(deviceAddress, function() {
+        chrome.test.assertNoLastError();
+        if (chrome.runtime.lastError)

[Jeffrey Yasskin, 2014/12/20 00:53:48]

Isn't this redundant with the assertNoLastError() call?

[armansito, 2014/12/20 01:24:28]

I'm not sure actually, as I mostly followed the other bluetoothPrivate API tests
as example and they do this check. I can test this and remove it if necessary.

+          chrome.test.fail(chrome.runtime.lastError);
+        chrome.test.succeed();
+      });
+    });
+  });
+}
+
+function assertFailure(message) {
+  if (!chrome.runtime.lastError)
+    chrome.test.fail('Expected failure but got success.');
+
+  if (chrome.runtime.lastError.message == message)
+    return;
+
+  chrome.test.fail('Expected error "' + message + '" but got "' +
+                   chrome.runtime.lastError.message + '" instead.');
+}
+
+chrome.test.runTests([testDisconnect]);