bluetooth: Add Device connection logic and accompanying user interface.

chrome/browser/resources/bluetooth_internals/adapter_broker.js

Index: chrome/browser/resources/bluetooth_internals/adapter_broker.js
diff --git a/chrome/browser/resources/bluetooth_internals/adapter_broker.js b/chrome/browser/resources/bluetooth_internals/adapter_broker.js
index ae9bfaae28d35ebe689de7cc5ff7634a2ce52976..f419086a379a4a943824dee9b0d89f7737efd623 100644
--- a/chrome/browser/resources/bluetooth_internals/adapter_broker.js
+++ b/chrome/browser/resources/bluetooth_internals/adapter_broker.js
@@ -27,6 +27,29 @@ cr.define('adapter_broker', function() {
     __proto__: cr.EventTarget.prototype,
 
     /**
+     * Creates a GATT connection to the device with |address|.
+     * @param {string} address
+     * @return {Promise<interfaces.BluetoothDevice.Device.proxyClass>}

[dpapad, 2016/11/10 19:05:02]

!Promise<!...>

[mbrunson, 2016/11/10 22:02:22]

Done.

+     */
+    connectToDevice: function(address) {
+      return this.adapter_.connectToDevice(address).then(function(response) {
+        if (response.result !=
+            interfaces.BluetoothAdapter.ConnectResult.SUCCESS) {
+          // TODO(crbug.com/663394): Replace with more descriptive error
+          // messages.
+          var errorString = Object.keys(

[dpapad, 2016/11/10 19:05:02]

Isn't this equivalent to 
interfaces.BluetoothAdapter.ConnectResult[response.result];

[mbrunson, 2016/11/10 22:02:22]

response.result is a number. ConnectResult is an object that represents an enum
which maps a string to a number.

This actually should be replaced by a for loop. Object.keys order is not
guaranteed but has been correct since I put this here.

+              interfaces.BluetoothAdapter.ConnectResult)[response.result];
+
+          throw new Error(errorString);
+        }
+
+        return interfaces.Connection.bindHandleToProxy(
+            response.device,
+            interfaces.BluetoothDevice.Device);
+      });
+    },
+
+    /**
      * Sets client of Adapter service.
      * @param {!interfaces.BluetoothAdapter.AdapterClient} adapterClient
      */